just had a play through/explore of about 8 or so different arenas, and can't find faults any of them seriously well done, also the destructible_targets are a nice touch shame it shows the tag for them tho
just an example of what i'm talking about, did a tournament at wercheg and was spawned on a horse, inital thought was this arena looks too crowded, but its not as a lot of the low parts of the ruins the horses can travel over, even in a later round i decided to run up the stairs on the central ruins i assumed the AI may have trouble getting up there but it all seems to work fine, only slight issue i have is mounted AI's getting stuck in places but then that's no different from how they get themselves stuck on walls anyways.
so after testing only thing i can think to add is what i said in my previous post, a list giving cities their corresponding number if for some reason u don't like an arena u can not install it.