If nobody from your instance has subscribed yet, it won't show up in searches. You can manually grab it by pasting "!community_name@instance.name" into the search field in the "Communities" tab up at the top. It'll say "not found" but then you should be able to find it by searching just the name or just going straight to the URL. Keep in mind it'll fetch the submissions but you won't be able to see old posts, only new posts from after you subscribed.
If nobody from your instance has subscribed yet, it won't show up in searches. You can manually grab it by pasting "!community_name@instance.name" into the search field in the "Communities" tab up at the top. It'll say "not found" but then you should be able to find it by searching just the name or just going straight to the URL. Keep in mind it'll fetch the submissions but you won't be able to see old posts, only new posts from after you subscribed.
I don't know what the procedure is for kbin.