Have you tried to search those communities first on dbzer0?

If you are the first one to search, you will have to search in a special way to allow dbze0 learn about the new community and then sync and federate.

This is true for all lemmy instances, if you are the first one to load the community on the instance.

Might be the case. But in all, welcome brother to lemmy. Hope you enjoy your place here like me.