I love these ideas! I think custom death messages are a great idea, especially if there are limited time things. I reckon they’d be even more fun to collect than tags!
Events sound good, but I think they’d be pretty hard to host, as much like global events players would have to leave their games to join. If there were a workaround to that, though, I’d be all in.
Lobby cosmetics would also be great imo. They may give off sort of Hypixelly vibes but they’d just be another fun little thing to collect.
Big +1 for these ideas!