acf-wpml-media.php

<?php

add_action('wpml_updated_translation_status', function ($data) {
  $postid = $data['translation_id'];
  $groups = acf_get_field_groups();
  foreach ($groups as $group) {
    $fields = acf_get_fields($group);
    foreach ($fields as $field) {
      if ($field['type'] == 'gallery') {
        $fieldValues = get_field($field['name'], $postid, false);
        foreach ($fieldValues as $fieldValues) {
          $translatedID = icl_object_id($fieldValues, 'attachment', false, ICL_LANGUAGE_CODE);
          //do something with this `$translatedID`
        }
      }
    }
  }
});