Some troubles with EasyAdmin 3 and KnpLabs/DoctrineBehaviors/translatable in Symfony 5.3

a2lix.yaml

a2lix_translation_form:
    locale_provider: default
    locales: [ru, en]
    default_locale: ru
    required_locales: [ru]
    templating: "@A2lixTranslationForm/bootstrap_4_layout.html.twig"

Brand.php

<?php

namespace App\Entity;

use App\Repository\BrandRepository;
use Doctrine\ORM\Mapping as ORM;
use Knp\DoctrineBehaviors\Contract\Entity\TranslatableInterface;
use Knp\DoctrineBehaviors\Model\Translatable\TranslatableTrait;
use Symfony\Component\HttpFoundation\File\File;
use Vich\UploaderBundle\Mapping\Annotation as Vich;

/**
 * @ORM\Entity(repositoryClass=BrandRepository::class)
 * @Vich\Uploadable
 * @ORM\HasLifecycleCallbacks()
 */
class Brand implements TranslatableInterface
{
    use TranslatableTrait;

    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="datetime_immutable")
     */
    private $createdAt;

    /**
     * @ORM\Column(type="datetime_immutable")
     */
    private $updatedAt;

    /**
     * @ORM\Column(type="boolean")
     */
    private $published;

    /**
     * @ORM\Column(type="string", length=255, nullable=true)
     */
    private $brandPhoto;

    /**
     * @Vich\UploadableField(mapping="brand_images", fileNameProperty="brandPhoto")
     * @var File|null
     */
    private $brandPhotoFile;

    /**
     * @ORM\Column(type="string", length=255, nullable=true)
     */
    private $brandLogo;

    /**
     * @Vich\UploadableField(mapping="brand_images", fileNameProperty="brandLogo")
     * @var File|null
     */
    private $brandLogoFile;

    /**
     * @ORM\Column(type="smallint")
     */
    private $priority;

    public function __construct()
    {
        $this->createdAt = new \DateTimeImmutable();
        $this->updatedAt = new \DateTimeImmutable();
    }

    public function getId(): ?int
    {
        return $this->id;
    }

    public function getCreatedAt(): ?\DateTimeImmutable
    {
        return $this->createdAt;
    }

    public function setCreatedAt(\DateTimeImmutable $createdAt): self
    {
        $this->createdAt = $createdAt;

        return $this;
    }

    /**
     * @ORM\PrePersist
     */
    public function setCreatedAtValue()
    {
        $this->createdAt = new \DateTimeImmutable();
    }

    public function getUpdatedAt(): ?\DateTimeImmutable
    {
        return $this->updatedAt;
    }

    public function setUpdatedAt(\DateTimeImmutable $updatedAt): self
    {
        $this->updatedAt = $updatedAt;

        return $this;
    }

    /**
     * @ORM\PreUpdate
     */
    public function setUpdatedAtValue()
    {
        $this->updatedAt = new \DateTimeImmutable();
    }

    public function getPublished(): ?bool
    {
        return $this->published;
    }

    public function setPublished(bool $published): self
    {
        $this->published = $published;

        return $this;
    }

    public function getBrandPhoto(): ?string
    {
        return $this->brandPhoto;
    }

    public function setBrandPhoto(?string $brandPhoto): self
    {
        $this->brandPhoto = $brandPhoto;

        return $this;
    }

    public function setBrandPhotoFile(File $brandPhoto = null)
    {
        $this->brandPhotoFile = $brandPhoto;

        // VERY IMPORTANT:
        // It is required that at least one field changes if you are using Doctrine,
        // otherwise the event listeners won't be called and the file is lost
        if ($brandPhoto) {
            // if 'updatedAt' is not defined in your entity, use another property
            $this->updatedAt = new \DateTimeImmutable('now');
        }
    }

    public function getBrandPhotoFile()
    {
        return $this->brandPhotoFile;
    }

    public function getBrandLogo(): ?string
    {
        return $this->brandLogo;
    }

    public function setBrandLogo(?string $brandLogo): self
    {
        $this->brandLogo = $brandLogo;

        return $this;
    }

    public function setBrandLogoFile(File $brandLogo = null)
    {
        $this->brandLogoFile = $brandLogo;

        // VERY IMPORTANT:
        // It is required that at least one field changes if you are using Doctrine,
        // otherwise the event listeners won't be called and the file is lost
        if ($brandLogo) {
            // if 'updatedAt' is not defined in your entity, use another property
            $this->updatedAt = new \DateTimeImmutable('now');
        }
    }

    public function getBrandLogoFile()
    {
        return $this->brandLogoFile;
    }

    public function getPriority(): ?int
    {
        return $this->priority;
    }

    public function setPriority(int $priority): self
    {
        $this->priority = $priority;

        return $this;
    }
    
    public function __get($method)
    {
        $arguments=[];
        return $this->proxyCurrentLocaleTranslation($method, $arguments);
    }
}

BrandCrudController.php

<?php

namespace App\Controller\Admin;

use App\Entity\Brand;
use EasyCorp\Bundle\EasyAdminBundle\Controller\AbstractCrudController;
use EasyCorp\Bundle\EasyAdminBundle\Config\Crud;
use EasyCorp\Bundle\EasyAdminBundle\Field\DateTimeField;
use EasyCorp\Bundle\EasyAdminBundle\Field\BooleanField;
use EasyCorp\Bundle\EasyAdminBundle\Field\TextField;
use App\Admin\Field\TranslationField;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use FOS\CKEditorBundle\Form\Type\CKEditorType;
use EasyCorp\Bundle\EasyAdminBundle\Field\Field;
use EasyCorp\Bundle\EasyAdminBundle\Field\ImageField;
use Vich\UploaderBundle\Form\Type\VichImageType;

class BrandCrudController extends AbstractCrudController
{
    public static function getEntityFqcn(): string
    {
        return Brand::class;
    }

    public function configureCrud(Crud $crud): Crud
    {
        return $crud
            //->renderContentMaximized()
            //->renderSidebarMinimized()
            // the Symfony Security permission needed to manage the entity
            // (none by default, so you can manage all instances of the entity)
            ->setEntityPermission('ROLE_ADMIN')
            ->setFormThemes(
                [
                    //'@A2lixTranslationForm/bootstrap_4_layout.html.twig',
                    'admin/a2lix_bootstrap_5_layout.html.twig',
                    '@EasyAdmin/crud/form_theme.html.twig',
                    '@FOSCKEditor/Form/ckeditor_widget.html.twig',
                ]
            );

    }

    public function configureFields(string $pageName): iterable
    {
        $fieldsConfig = [
            'title' => [
                'field_type' => TextType::class,
                'required' => true,
                'label' => 'Заголовок',
            ],
            'description' => [
                'field_type' => CKEditorType::class,
                'required' => true,
                'label' => 'Текст',
            ],
        ];

        return [
            DateTimeField::new('createdAt')->setColumns(6),
            BooleanField::new('published')->setColumns(6),
            Field::new('brandPhotoFile')->onlyOnForms()->setFormType(VichImageType::class)->setColumns(6),
            ImageField::new('brandLogo')->onlyOnIndex()->setBasePath('/upload/brand-images/'),
            Field::new('brandLogoFile')->onlyOnForms()->setFormType(VichImageType::class)->setColumns(6),
            Field::new('priority'),
            TranslationField::new('translations', 'Переводы', $fieldsConfig)
                ->setRequired(true)
                ->hideOnIndex(),
        ];
    }
}

BrandTranslation.php

<?php

namespace App\Entity;

use App\Repository\BrandTranslationRepository;
use Doctrine\ORM\Mapping as ORM;
use Knp\DoctrineBehaviors\Contract\Entity\TranslationInterface;
use Knp\DoctrineBehaviors\Model\Translatable\TranslationTrait;
use Knp\DoctrineBehaviors\Contract\Entity\SluggableInterface;
use Knp\DoctrineBehaviors\Model\Sluggable\SluggableTrait;

/**
 * @ORM\Entity(repositoryClass=BrandTranslationRepository::class)
 */
class BrandTranslation implements TranslationInterface, SluggableInterface
{
    use TranslationTrait;
    use SluggableTrait;

    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $title;

    /**
     * @ORM\Column(type="text")
     */
    private $description;

    public function getId(): ?int
    {
        return $this->id;
    }

    public function getTitle(): ?string
    {
        return $this->title;
    }

    public function setTitle(string $title): self
    {
        $this->title = $title;

        return $this;
    }

    public function getDescription(): ?string
    {
        return $this->description;
    }

    public function setDescription(string $description): self
    {
        $this->description = $description;

        return $this;
    }

    /**
     * @return string[]
     */
    public function getSluggableFields(): array
    {
        return ['title'];
    }
}

BrandTranslationCrudController.php

<?php

namespace App\Controller\Admin;

use App\Entity\BrandTranslation;
use EasyCorp\Bundle\EasyAdminBundle\Controller\AbstractCrudController;

class BrandTranslationCrudController extends AbstractCrudController
{
    public static function getEntityFqcn(): string
    {
        return BrandTranslation::class;
    }

    /*
    public function configureFields(string $pageName): iterable
    {
        return [
            IdField::new('id'),
            TextField::new('title'),
            TextEditorField::new('description'),
        ];
    }
    */
}

easy_admin.yaml

easy_admin:
    design:
        form_theme:
            - '@EasyAdmin/form/bootstrap_4.html.twig'
            - '@FOSCKEditor/Form/ckeditor_widget.html.twig'
            - '@A2lixTranslationForm/bootstrap_4_layout.html.twig'
            - '@VichUploader/Form/fields.html.twig'
    entities:
        # List the entity class name you want to manage
        Brand:
            class: App\Entity\Brand
            form:
                fields:
                    - {property: 'brandPhotoFile', type: 'VichImageType'}
                    - {property: 'brandLogoFile', type: 'VichImageType'}
        Style:
            class: App\Entity\Style

TranslationField.php

<?php

namespace App\Admin\Field;

use A2lix\TranslationFormBundle\Form\Type\TranslationsType;
use EasyCorp\Bundle\EasyAdminBundle\Contracts\Field\FieldInterface;
use EasyCorp\Bundle\EasyAdminBundle\Field\FieldTrait;

final class TranslationField implements FieldInterface
{
    use FieldTrait;

    public static function new(string $propertyName, ?string $label = null, $fieldsConfig = []): self
    {
        return (new self())
            ->setProperty($propertyName)
            ->setLabel($label)
            ->setFormType(TranslationsType::class)
            ->setFormTypeOptions(
                [
                    'default_locale' => '%locale%',
                    'fields' => $fieldsConfig,
                ]
            );
    }
}

Finally I found a solution:
If I add magic method __get() in Brand.php

    public function __get($method)
    {
        $arguments=[];
        return $this->proxyCurrentLocaleTranslation($method, $arguments);
    }

everything works great

public function __get($name)
    {
        $method = 'get'. ucfirst($name);
        $arguments = [];
        return $this->proxyCurrentLocaleTranslation($method, $arguments);
    }

Можно и так