I don't know if this has been asked before, but it would be nice if we could get a couple of predetermined reasons to decline people. As someone who only uses this to look for groups, I often get the situation where I apply to a wait list, wait a few minutes, then get that horn that means "declined" with absolutely no idea on why I was declined. This means I get no feedback on what I did wrong, let alone something I can work with to improve my chance to get into the next group.
Another point of annoyance: "wait list full". really annoying. it's something that as a joiner, you can do nothing about except maybe try again a few minutes later, in the hope that the creator by then has accepted or denied enough people for you to get on the list. I know this is a problem that requires the user to do something about it and I don't know how big the wait list is currently, but it feels like it's too small. If increasing the wait list is too intensive, there are alternatives. you could save any requests to a full wait list on the joiner side and save just the RealID on the creator side. then, when the wait list has room again, you can send a signal to all joiners in the RealID list who can then resend their request.