He wrote a band piece called "La Fiesta Mexicana" (this is the last movement) and it is just plain hard to play. Not that the notes are terribly difficult, in fact, technically it is pretty easy, but to make it sound "right" well it is a trick of balance and style.
Anyway, a friend of mine did his spring break in Mexico that year and brought back a "record"...yes a 33 1/3 vinyl. It had a street band..you know..one of those bands you hear on Univision when you are passing channels?...and they were playing this...almost note for note...all the tunes...ohmygod.
Moral of the story: First time in my experience an WASP stole something from a Mexican and got all the credit and did little of the work. Not the first time I'm sure and in the 40 years since, not the last.