Not quiteAlso realized something!
Spoils for True Pacifist run:
The statue in the waterfall area for the piano puzzle is of Asriel. The music it plays when you give it the umbrella is the song that plays during the story telling of the original fallen child and Asriel and is of monster with horns like the boss monster species.
edit I misread, this is pretty on point I thought you meant the piano room itself
call undyne there