they can track you everywhere, supreme fist, challenge, boss fights, arena.its quite easy, all they have to do is use the mod in places where it cant be tracked by the players etc to get reported, if their is a leader board then its easy to catch someone cheating. so cheat in places/modes where its hard for people to track you
the only thing where they can't track is the area where you don't need mods.
how do they track you might ask? literally every fight is recorded and watchable for everyone.