Yeah it’s a tricky one to fix because the federated nature of everything means there’s probably no instance that has every possible community indexed in search.
That’s where tools like browse.feddit.de come in but that’s a little bit finicky too and I’m not sure how things get indexed there.
Saw someone was building a more advanced search interface yesterday but I can’t remember the URL now, it looked promising though so will come back and update you when I find it!
P.s I didn’t post the link as some kind of passive aggressive thing I just thought you’d like to see it 😄