The search function on kbin.social shows lemmy communities when someone on kbin.social first subscribes to that lemmy community. It will not show up if no one has subscribed to that community before you.
This is why niche communities will be hard to find, popular communities will be easy to search.
Even within kbin instances communities are not searched globally. For example, I made a Korean language community on kbin.social, if I search for it on another kbin instance like fedia.io, it will not show up. It’s the same when you search on any lemmy instance
I show this comic every once in a while to people if they don’t know much about Korean :)
I also have always liked this video for going a bit deeper into the history and reasoning behind the hangul alphabet and how it was made.