This may be a controversial opinion but I think it's useless to split up conversations across 30.000 communities.
We need maybe 30 communities at this point. Don't believe me? Look at forums.
This is again a self inflicted problem with Lemmy, similar to having one giant instance. It seems people go out of their way and make unwise decisions, like creating tons of communities without having an actual problem to solve.
In this federated world, you need to go to the top most populated instances, make a user account, then subscribe to your community from each instance. This gets your posts into the all feed.
Advertise your community in new communities
Pump the numbers to get into trending communities.
Make a bunch of cross posts, to "accidently" raise awareness.
Tell people about it in comments with. Oh hey, we talk about this stuff in !community@example.ml