I think this idea is neat however, I believe this should be implemented carefully.
Room’s should be hand-picked or reviewed to have the option to be in a weekly challenge. The example of spending 15 minutes in a room can already be measured by RecRoom. But for more nuanced challenges, those should be reviewed to be thrown into the mix.
This could definitely promote more activity in rooms and community collaboration between rooms, like seen in invasion events.
However, I think the rewards should be tweaked a little. Sure, UGC avatar studio items can be a reward, but I think people would appreciate rolling in new or old skins (since RecRoom has already completely abolished rare skins by selling them again), or a 5 star box, or expensive consumables, like a bubbly.
Overall interesting suggestion!