But that check knows only what the whole message looks like not just what change the last edit was. I’d say that having a wiki edit somehow test only the changes made in the most recent edit would be a feature request. That seems . . . complicated.
The best work-around I can think of is to up the max mentions per post to a really big number and hope that no one behaves badly.
A worse one is using just the username with no @ or quoting @username , which is pretty ugly since you’ve now lost the beauty of mentions.