You could remove “Sichtbarkeit” from the trigger,it should trigger no matter if the note is public or not then.
The big question is, if it’s a use case that you guys can use private notes that shouldn’t concern the customer.
Problem is, when changing the visibility of the article after posting it, the trigger can’t fire for it anymore.
That is not an option as it would sent the customer an e-mail with the last article even when the note is marked “internal”. I just tried it and the email is sent for both external and internal notes.
I understand, that it is not often used but in our case, a note is internal per default. If someone forgets to make it external, the client doesn’t get an email.
If the change from “internal” to “external” is marked as an “update” of the ticket, then it would trigger.
Not a big deal but maybe worth looking at in the future.