It's not a literal allusion to satan and never was, it's akin to the idiom "the devil is in the details."

It was nearly or actually impossible to harmonize or progress tritones while following the medieval "rules" for church music composition. So it is someone complaining about their work, not a statement about musical morality or whatever.

multiply by 3^m/2^n is a human construction. and it breaks after a bunch of m,n. to expect it "not to break" is well an expectation. nature always has a comma, its not clockwork.