Add post date to post notification newsletter

We’ve been using MailPoet2 for several years now and I would like to upgrade to MailPoet3.
But there’s one thing I can’t figure out.

We need the post date in the newsletter that sends out post notifications.

We had built a workaround in MailPoet2 to replace the author with the post date (by replacing a line in the helpers/articles.php). It was a messy solution because it had to be changed manually everytime we updated the plugin, but it worked.

In MailPoet3 though, I don’t see any way to add the post date to the post notifications.

I tried building a custom shortcode, but it doesn’t work:

add_filter('mailpoet_newsletter_shortcode', 'mailpoet_add_date', 10, 5);

function mailpoet_add_date($shortcode, $post) {
  // always return the shortcode if it doesn't match your own!
  if ($shortcode !== '[custom:eventdate]') return $shortcode; 
  
 	$eventdate .= "<b>".get_the_time('d.m.Y' , $post['ID'])."</b>";
  
  return $eventdate;
}

Adding “[custom:eventdate]” to the author or category line in display options does not work, though. I can think of a lot of reasons why it doesn’t :-). Maybe the variable $post is not available here? Or the input in the fields for display options cannot work with shortcodes?

Is there any way to have the post date appear in a post notifications newsletter?

Thanks a lot for your help!
Alicia