in this tuto, I'll show you how to force form element to use specific template in Drupal 8.
/**
* @param $variables
* @param $hook
* @param $info
*/
function THEMENAME_preprocess_form_element(&$variables, $hook, &$info)
{
if (isset($variables['element']['#id'])) {
$id = $variables['element']['#id'];
if ( $id == "FORM_ELEMENT_ID") {
$info['template'] = str_replace('_', '-', $hook) . '--' . $id;
}
}
}
