_content_translation_preprocess_language_content_settings_table

_content_translation_preprocess_language_content_settings_table(&$variables)

function _content_translation_preprocess_language_content_settings_table(&$variables) {
  // Alter the 'build' variable injecting the translation settings if the user
  // has the required permission.
  if (!\Drupal::currentUser()->hasPermission('administer content translation')) {
    return;
  }

  $element = $variables['element'];
  $build = &$variables['build'];

  array_unshift($build['#header'], array('data' => t('Translatable'), 'class' => array('translatable')));
  $rows = array();

  foreach (Element::children($element) as $bundle) {
    $field_names = !empty($element[$bundle]['fields']) ? Element::children($element[$bundle]['fields']) : array();
    if (!empty($element[$bundle]['translatable'])) {
      $checkbox_id = $element[$bundle]['translatable']['#id'];
    }
    $rows[$bundle] = $build['#rows'][$bundle];

    if (!empty($element[$bundle]['translatable'])) {
      $translatable = array(
        'data' => $element[$bundle]['translatable'],
        'class' => array('translatable'),
      );
      array_unshift($rows[$bundle]['data'], $translatable);

      $rows[$bundle]['data'][1]['data']['#prefix'] = '<label for="' . $checkbox_id . '">';
    }
    else {
      $translatable = array(
        'data' => t('N/A'),
        'class' => array('untranslatable'),
      );
      array_unshift($rows[$bundle]['data'], $translatable);
    }

    foreach ($field_names as $field_name) {
      $field_element = &$element[$bundle]['fields'][$field_name];
      $rows[] = array(
        'data' => array(
          array(
            'data' => drupal_render($field_element),
            'class' => array('translatable'),
          ),
          array(
            'data' => array(
              '#prefix' => '<label for="' . $field_element['#id'] . '">',
              '#suffix' => '</label>',
              'bundle' => array(
                '#prefix' => '<span class="visually-hidden">',
                '#suffix' => '</span> ',
                '#plain_text' => $element[$bundle]['settings']['#label'],
              ),
              'field' => array(
                '#plain_text' => $field_element['#label'],
              ),
            ),
            'class' => array('field'),
          ),
          array(
            'data' => '',
            'class' => array('operations'),
          ),
        ),
        'class' => array('field-settings'),
      );

      if (!empty($element[$bundle]['columns'][$field_name])) {
        $column_element = &$element[$bundle]['columns'][$field_name];
        foreach (Element::children($column_element) as $key) {
          $column_label = $column_element[$key]['#title'];
          unset($column_element[$key]['#title']);
          $rows[] = array(
            'data' => array(
              array(
                'data' => drupal_render($column_element[$key]),
                'class' => array('translatable'),
              ),
              array(
                'data' => array(
                  '#prefix' => '<label for="' . $column_element[$key]['#id'] . '">',
                  '#suffix' => '</label>',
                  'bundle' => array(
                    '#prefix' => '<span class="visually-hidden">',
                    '#suffix' => '</span> ',
                    '#plain_text' => $element[$bundle]['settings']['#label'],
                  ),
                  'field' => array(
                    '#prefix' => '<span class="visually-hidden">',
                    '#suffix' => '</span> ',
                    '#plain_text' => $field_element['#label'],
                  ),
                  'columns' => array(
                    '#plain_text' => $column_label,
                  ),
                ),
                'class' => array('column'),
              ),
              array(
                'data' => '',
                'class' => array('operations'),
              ),
            ),
            'class' => array('column-settings'),
          );
        }
      }
    }
  }

  $build['#rows'] = $rows;
}