I've been searching a lot, and finally found out that in order to show a moderator on your forum index, you need to edit individual permissions of that user to be able to moderate those forums. Can't you make it so that you can assign a certain usergroup to become forum moderators, and give the option to turn it being showed on/off or something? Maybe a forum configuration option where you can specify groups/users to show up as moderators?
Aside from that, I found out that if I have a sub-category of a main index category, and make several forums in that category it doesn't list those forum moderators as being moderators on the main index sub-category page? Only below the respective forums themselves.
Any chance this will get adjusted in the future, with perhaps more customizable options for forums and it's moderators?