I have been heavily using the kde bug tracker, as I have run into a lot of issues with kde.
And it really bugs me how I cannot edit bugs in the bug tracker. 
I know there are probably workflow-related reasons for bugs not being reported at kde gitlab.
But not having an edit button is really a huge hindrance, especially for users with language barriers or ADHD. So I would love seeing this fixed.
Unfortunately it’s not a feature that Bugzilla has. We can’t add it.
Hm I got told bugzilla added an edit button a while ago.
Btw having a bugzilla reference and a version number somewhere on bugs.kde.org would have also been neat. 
I kind of assumed this was a self made kde thing as I had not seen another bugzilla before.
Oh: hasn’t been released yet.
The bug report you linked to is about letting authors edit their posts - and is closed as “WONTFIX” (I wasn’t interested enough to follow the reasoning, though from reading the last comment from 4 years ago, it seems that there isn’t).
The ticket for actually editing comments is a different one and that was ostensibly “fixed”, but it requires the editor to have the special permission “edit bugs” which is probably only afforded to admins. I can understand why some people would be loath to have any one just edit comments they made on a public tracker that developers rely on - it can be used to remove important information and then feign ignorance. I know for a fact that these kind of abuses have been happening on the Github issue tracker - even though that one has an edit history feature, which I don’t think Bugzilla has.
@betalars, likewise. You can follow bugs.kde.org/show_bug.cgi?id=334299.