cannot change admin nickname
oh, I have no skills to investigate that, but I don't see how JS could be involved. I'd rather think, because it generated a slug like 2-2-2-2-, that it's related to some sort of revisions or multiple savings that occurred somewhere in time
luckily this forum is not used by the public yet, but I have no idea how to get over this
When you try to change your id and save, can you previously press F12 in your browser and check for JS errors in console?
If there are no errors before and after saving, then JS errors are not your problem for that particular problem.
I actually don't have any JS errors in consolle, and F12 is not revealing anything after saving