Nonono you don't understand. What you linked to extends the Direct Sound limit from 5 to 12. In the GBA games, only 5 Direct Sound instruments can be playing at once. This allows 12. This does NOT allow a Sappy song to have 12 instruments, the limit is still 10. All it does it make it so that up to 12 Direct Sound instruments can be playing at once, which is possible even with 10 tracks, since you can have a single track play more than one note at the same time. In other words, in the GBA games unmodified, you can only have 5 Direct Sound instruments playing at once, and 5 "Game Boy" instruments playing at once, but you must limit it to 10 Sappy tracks total. With this extension, you can now have up to 12 Direct Sound instruments playing at once, and 5 "Game Boy" instruments playing at once, but you're still limited to 10 Sappy tracks.
What tajaros was talking about is if its possible to extend the maximum amount of Sappy tracks to 16. The thing you linked to just makes it so that you can have 12 Direct Sound notes playing at once, but the track limit is still 10.
