I've had the same problem trying to search for other smallish communities from Mastodon (although not all, can't actually figure out the pattern just yet).
What I've found is that after searching for them (format @simpleliving@lemmy.ml) and getting no results, if I come back a few hours later and searching again they then do seem to show up? Almost like Mastodon just has a really long delay for pulling in new communities.
It's not much immediate help but it might be worth checking again in a bit.
Edit: for anyone else confused, this seems to be one of those threads that only lets you reply if you explicitly select a language