lemmy.ml is down right now. You’re going to have to wait until it’s back up to ask them - this question/answer is just local to lemm.ee until it comes back up and can appropriately federate.
When you’re trying to find a community, in the search type in the whole URL. So for your example you should be able to make the instance find the community by typing in https://hobbit.world/c/hobbit_art in search all.
Memmy’s on the App Store now. It does still have a TestFlight if there are any spots available but the app store’s version is currently up to date.