I'll just chime in and say that I really like this idea. I especially love how you seem to be trying to let this be as democratic and flexible as possible, which to be honest I think has been somewhat of an issue with the Tapas Character Fight Club (TCFC).
I'd like to raise the question of how the results of events will be published. With TCFC, all the events are supposed to be published on one person's channel, which makes it so everyone kind of has to approve everything with this one person (who has been hard to get in touch with). Personally I suggest the Colosseum allows each working group to agree on which channel to publish their results on, but I'd love to hear your ideas 