https://store.pianodisc.com/pages/terms-of-service-and-condi...
I don't see details about them mentioning and decoder or encoder.
IANAL. But I think reverse engineering their data structure, identifying a security measure - even one as weak as obfuscation, and publishing code to circumvent it is clearly against your license.
If the security measures exist in plain sight, as they apparently do, are they allowed to be discussed?
I reckon that if OP posts the encoder/decoder software that'd be against some sort of license clause. However in the age of AI who cares about the software at this point? Anyone can prompt their own private version into existence.
Just thinking out loud here. I have not considered AIs use as personal "cheat engines".