

Best place to find communities your instance may not already know about is this site
(remote communities only federate over once a user subscribes)
Make sure to have both English and Undefined selected in your profile settings (next release should fix this)
There’s definitely more I’ve accumulated over the past couple years but those two come to mind first. There is also a tool that automates the new community federation process here if your admins participate.
Feel free to reach out in the future if there’s anything else I could clear up.