Tetris (NES) Music hack help

[rockybaldwin4]

So I was listening to some remixes on YouTube and found this remix of Katyusha:https://www.youtube.com/watch?v=ez9DhkZvXXg
I really liked the song, and wanted to replace the B-theme with this. However, I can't seem to find any documentation whatsoever on where I would be able to even find this data, let alone edit it. Is this a dead end?

[Jorpho]

It's not impossible to change music, but generally there is no easy way to do it, no.  That would require either reverse-engineering the music engine, or replacing the existing music engine with Famitracker (or Famitone) or the like.

ETA: I should clarify that, NES Tetris being the beloved game that it is, there has been much work done on disassembling the ROM.
https://github.com/CelestialAmber/TetrisNESDisasm