Translate Task Priority field

AppBundle.php

<?php

namespace AppBundle;

use Symfony\Component\HttpKernel\Bundle\Bundle;

class AppBundle extends Bundle
{
}

AppExtension.php

<?php
namespace AppBundle\DependencyInjection;

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\Config\FileLocator;
use Symfony\Component\HttpKernel\DependencyInjection\Extension;
use Symfony\Component\DependencyInjection\Loader;

class AppExtension extends Extension
{
    const ALIAS = 'app';

    /**
     * {@inheritDoc}
     */
    public function load(array $configs, ContainerBuilder $container)
    {
        $loader = new Loader\YamlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
        $loader->load('services.yml');
    }

    /**
     * {@inheritDoc}
     */
    public function getAlias()
    {
        return self::ALIAS;
    }
}

bundles.yml

bundles:
    - { name: AppBundle\AppBundle, priority: 1000 }

messages.en.yml

Normal: New Normal

services.yml

services:
  task_type.form_type_extension:
      class: AppBundle\Form\Extension\TaskTypeTypeExtension
      tags:
          - { name: form.type_extension, extended_type: Oro\Bundle\TaskBundle\Form\Type\TaskType }

TaskTypeTypeExtension.php

<?php
// Form\Extension
namespace AppBundle\Form\Extension;

use Oro\Bundle\FormBundle\Utils\FormUtils;
use Oro\Bundle\TaskBundle\Form\Type\TaskType;
use Symfony\Component\Form\AbstractTypeExtension;
use Symfony\Component\Form\FormBuilderInterface;
use Symfony\Component\Form\FormEvent;
use Symfony\Component\Form\FormEvents;

class TaskTypeTypeExtension extends AbstractTypeExtension
{
    /**
     * {@inheritdoc}
     */
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        $builder->addEventListener(
            FormEvents::PRE_SET_DATA,
            function (FormEvent $event) {
                $form = $event->getForm();

                FormUtils::replaceField($form, 'taskPriority', ['translatable_options'=> true]);

            }
        );
    }

    public function getExtendedType()
    {
        return TaskType::class;
    }
}