Both kantele.lua and huilu.lua are simply full of broken, badly written code.
The fix was to rewrite them in their entirety, going that far, I decided that might as well make an appendable song list. Really there is nothing left of the original code.

Hello, I'm working on a content mod and want to fix & add new musical songs to the game but am having difficulty figuring out why the kantele is broken in the basegame.
I don't wan't to ask people to download an entire seperate mod for one of mine to function either though, so would you mind letting me integrate this mod into my current project with credit?

If not, could you tell me what causes the vanilla bomb song, & custom songs to break with the kantele if you figured out the cause?

Thankyou