Sounds like a problem with Memmy. Does this link work? https://lemm.ee/c/sfah@hilariouschaos.com
You should be able to search communities in your app and could have searched “sfah@hilariouschaos.com” too.
But basically communities on Lemmy are in the form of “name@host”. The “name” can be whatever someone wants, and the “host” is the website / Lemmy instance where that community originates from. But because it is federated it’s all available everywhere (generally speaking). For example, if you visit https://lemmy.world/c/sfah@hilariouschaos.com it should be the same content just loaded via lemmy.world instead of lemme.ee. However if theoretically someone went and made a “sfah@lemmy.world” community, that would be a completely separate community from the above, hosted on a different Lemmy instance.
I’m pretty sure @ruud@lemmy.world has said before what he uses. I thought back in the day it was publicly listed with the expenses, but I couldn’t find it.
The most recent update I found was here: https://lemmy.world/post/75556
But it could definitely be old information, I’d take the other commenter’s advice and ask in the admin channel to be sure.