Submission query alter by entity ID

I have a webform called Event Registration which has 3 fields: name, email and event(entity reference). I created a block view and I want to display the number of users registered to a certain event. I wanted to add contextual filters to the view but for some reason my custom fields are not displaying in the block, only global. I then attempted to alter the query but I have been unsuccessful in adding this condition to it.

function event_registration_views_query_alter(ViewExecutable $view, QueryPluginBase $query) {

  if ($view->id() == 'event_register') {
    $webform = \Drupal\webform\Entity\Webform::load('event_subscribe');
    $node = Drupal::routeMatch()->getParameter("node")->id();
    if ($webform->hasSubmissions()) {
      $query = \Drupal::entityQuery('webform_submission')
        ->condition('webform_id', 'event_subscribe')
        ->condition('event', $node);
      $result = $query->accessCheck(FALSE)->execute();

What am I doing wrong?