I think I'm right on this, but if you were able to AUP from J to F, where the J was a UUA from a revenue W fare, you DON'T get additional Avios and TPs beyond the original W fare. Is that right? Currently MMB shows both legs of my upcoming flight in the U bucket.

If I were able to get 210 rather than 90 TPs on one leg, then that's me back to Gold, so it's a very material consideration.