A user should be able to see which moderator is reponsible for which category, for example by a small info bar/text for each category (automated).
There should maybe be a group for every category where a simple non-global moderator exists, manually this is way too much work. In posts, they should be highlighted using some badge - but ONLY for that category which they are moderator. I don't want to see his/her "Mod"-Badge when he/she posts in a category which isn't where she is a moderator if that makes sense.
It would be nice to see all moderators of a group when clicking on a category. Like a small panel or something.