How to reload flagging form via ajax?

My task is to ajaxify complex flag form (with additional fields). I need this because the default ajax flag does not dupport fiedls. I need to have the flagging form for create flag and then update it when flagging has been created.

I want to place custom flagging ajaxified form in my template First I get form build:

$term = $variables['term'];
$flag = \Drupal::service('flag')->getFlagById('subscribe_term');
$flagging_entity = \Drupal::service('flag')->getFlagging($flag, $variables['term']);

if (!$flagging_entity) {
  $flagging_entity = \Drupal::entityTypeManager()->getStorage('flagging')->create([
    'uid'         => \Drupal::currentUser()->id(),
    'session_id'  => NULL,
    'flag_id'     => $flag->id(),
    'entity_id'   => $term->id(),
    'entity_type' => $term->getEntityTypeId(),
    'global'      => $flag->isGlobal(),
  ]);
}

$form = \Drupal::entityTypeManager()
    ->getFormObject('flagging', 'edit')
    ->setEntity($flagging_entity);

$variables['flag'] = \Drupal::formBuilder()->getForm($form);

The form works ok.

Then I alter the form ad add ajax callback:

$form['actions']['submit']['#ajax'] = [
  'callback' => 'mymodule_flag_form_ajax_callback',
  'effect'   => 'fade',
];

And then in the ajax callback I try to get the same form:

$render_selector = ".flag-form-wrapper";
$response = new AjaxResponse();
$form_object = $form_state->getFormObject();
$flagging_entity = $form_object->getEntity();

$flagged_entity_field = $flagging_entity->get('flagged_entity')->getValue();

if ($flagged_entity_field) {
  $tid = $flagged_entity_field[0]['target_id'];
  $term = \Drupal::entityTypeManager()->getStorage('taxonomy_term')->load($tid);

  if ($term) {
    $flag = \Drupal::service('flag')->getFlagById('subscribe_term');
    $flagging_entity = \Drupal::service('flag')->getFlagging($flag, $term);

    if (!$flagging_entity) {
      $flagging_entity = \Drupal::entityTypeManager()->getStorage('flagging')->create([
        'uid'         => \Drupal::currentUser()->id(),
        'session_id'  => NULL,
        'flag_id'     => $flag->id(),
        'entity_id'   => $term->id(),
        'entity_type' => $term->getEntityTypeId(),
        'global'      => $flag->isGlobal(),
      ]);
    }

    $form_new = \Drupal::entityTypeManager()
        ->getFormObject('flagging', 'edit')
        ->setEntity($flagging_entity);
    $form_build = \Drupal::formBuilder()->getForm($form_new);

    $response->addCommand(new HtmlCommand($render_selector, $form_build));
  }
}

but I get the following exception: FormAjaxException

So what I am doing wrong and how to refresh the form using ajax?