A PHP-Class to make fields translatable

functions.php

add_action( 'acf/init', function() {
	acf_add_local_field_group([
		'key'        => 'myGroup',
		'title'      => 'Group',
		'multilang'  => true,
		'menu_order' => 50,
		'fields'     => [
			[
				'key'   => 'field_myField',
				'name'  => 'myField',
				'label' => 'my field',
				'type'  => 'text',
			],
		],
		'location'   => [
			[
				[
					'param'    => 'options_page',
					'operator' => '==',
					'value'    => 'myPage',
				],
			],
		],
	]);
} );

Polylang.php

<?php

namespace SayHello\Theme\Package;

/**
 * @author Nico Martin <[email protected]>
 */
class Polylang
{
	public $translatedNames = [];

	public function run()
	{
		if ( ! function_exists('pll_current_language')) {
			return;
		}
		
		add_filter('acf/validate_field_group', [$this, 'multilangGroup']);
		add_filter('acf/load_value', [$this, 'multilangField'], 20, 3);
		add_filter('acf/load_reference', [$this, 'manipulateNameReference'], 20, 2);
	}

	public function multilangGroup($group)
	{
		if ( ! array_key_exists('multilang', $group) || $group['multilang'] !== true) {
			return $group;
		}

		$fields    = $group['fields'];
		$newFields = [];
		foreach (self::languages() as $key => $name) {
			$newFields[] = [
				'key'   => $group['key'] . '-langtab-' . $key,
				'name'  => $group['key'] . '-langtab-' . $key,
				'label' => $name,
				'type'  => 'tab',
			];
			foreach ($fields as $field) {
				acf_get_local_store('fields')->set($field['name'], $field);
				$this->translatedNames[$field['name']] = $field['name'] . '-polylang-' . pll_current_language();
				$field['key']                          = $field['key'] . '-polylang-' . $key;
				$field['name']                         = $field['name'] . '-polylang-' . $key;
				$newFields[]                           = $field;
			}
		}

		$group['fields'] = $newFields;

		return $group;
	}

	public function multilangField($value, $post_id, $field)
	{
		if (is_admin() || $value) {
			return $value;
		}

		$newKey = $field['key'] . '-polylang-' . pll_current_language();
		if (acf_maybe_get_field($newKey, $post_id)) {
			return get_field($newKey, $post_id, false);
		}

		return $value;
	}

	public function manipulateNameReference($reference, $field_name)
	{
		if ($reference === null && is_string($field_name) && array_key_exists($field_name, $this->translatedNames)) {
			return $this->translatedNames[$field_name];
		}

		return $reference;
	}

	public static function languages()
	{
		if ( ! function_exists('pll_the_languages')) {
			return [explode('_', get_locale())[0]];
		}

		$langs = get_terms('term_language', [
			'hide_empty' => false,
		]);

		$return = [];
		foreach ($langs as $lang) {
			$key          = str_replace('pll_', '', $lang->slug);
			$return[$key] = $lang->name;
		}

		return $return;
	}
}