Happy to see this go wherever it goes Vic
King Ofeo has always fascinated me
There was a pubblished sizeable study of it back in the sixties, - I was put off by all the 'funny writing" - I regret never having bought it now.

"the ballad form is unknown in these languages"
Depends what you mean by the term - narrative songs are certainly rare. but there are a few (I believe - I'm not an Irish speaker)
Joe's version of Lord Randal ir repetitive rather than narrative - it was suggested once that he made it himself from his contact with Ewan and the revival, but we have the recording o the interview where he sings it for Ewan and Peggy, and Junior Crehan's version confirms that an Irish text was current when he learned it early in the 20th century.
One of the articles I'm thinking of putting in this package is by Hugh Shield who (I think) deals with Irish language ballads - it's a long time since I read it.
Jim