I think lemmy.ml is pretty overloaded currently, from what I’ve read. Also, even for a German server I wanted to join a community on the search result took several seconds to appear. (much longer than what I’m used to from Mastodon).

Looks like it’s showing up now!

Usually if it isn’t immediately available in the search, just give it a few minutes then try again, as we have to download the metadata and a few posts from lemmy.ml with each new community searched and that can take some time.