The Aluminum Falcon said:
...They didn't make clear that the "Swan Lake" in the 1931 Spanish version was the same recording without the speed issues; it could possibly have been another recording.

I'm sure it would be. The Spanish version was filmed alongside the US version with all the same sets, many of the same costumes and even most of the same sound effects. I don't see anything happening here that isn't a part of a proper restoration. Can't wait for the Universal Monsters Blurays!