The UX has a lot of friction, and by that I mean, you have a identical Pop-Up menu of checkboxes for both adding and removing tags:

Why not just leave set tags only? When you check the box, it marks, when you uncheck it, it unmarks, simple like that.
The "add tags" and "edit tags" also could be converted to only one menu...

Also, I cant find a way to remove tags using the catalog list as well, the only option available is to create a "add tag" collumn. But the best thing would be if you clicked a tag there it would tag it, and if you clicked again it would untag it.
Best!
XYplorer Beta Club