Shouldn't this be, "Cyrhaedda i'n gynnar"? Or is it OK to not contract the "i" and "yn"?
It is usual to contract them unless there is a specific purpose in not doing so.
No. I think it is more likely that nobody realised in time that 'n was needed as a separate item in the database at an earlier stage.
We know that now, so version 2 of the Welsh course database is being designed to be more flexible.