Default email containing details about what has been moderated - not working properly

Yes, if you’re familiar with coding please try using the suggested filter, it accepts 2 parameters: the errors array and the form object. You can get listing from the form object:

$form->get_model();

And then check any listing details and add custom errors to the errors array. You can check a sample snippet here How to set up max tags users can choose - #3 by andrii