It probably is slower for us "mature" beginners, but I suspect progress is more a function of practice time than of age.
It's great that you know the Ungars. The acoustic band I practice with regularly does Jay's "Ashokan Farewell" and "The Lovers' Waltz." I don't know Jay, but our fiddle-playing band leader is acquainted with him from many years back. At the band's request, I wrote lyrics to Lovers' Waltz, and we've performed them as well. I sent them to Jay and he was very kind to reply, but others have sent him lyrics too, and he says he's decided just to keep it as an instrumental piece.
Thanks for your note.