I'm a little confused about some of this as well, particularly missing communities. One I'd like to join is godot@lemmy.ml but it's missing from kbin. Has it not just been synced yet? Or is it not federated or something?
I was also curious about issues like this. You can see that community from kbin here: https://kbin.social/m/godot@lemmy.ml but also if you go to that page it says "The magazine from the federated server may be incomplete. Browse more on the original instance." And indeed, from kbin you can only see 4 posts and 15 subscribers, but from the lemmy.ml page you can see 109 posts and 377 subscribers. I'm not sure what the issue is. Best I can tell, kbin is just a fairly new service and things are still being figured out.
/kbin meta
Magazine dedicated to discussions about the kbin itself. Provide feedback, ask questions, suggest improvements, and engage in conversations related to the platform organization, policies, features, and community dynamics. ---- * Roadmap 2023 * m/kbinDevlog * m/kbinDesign