Thanks mate! You're always so helpful I didn't thought this was also controlled by PSAI given that it uses SoundManager to control the parameter while there is MusicManager...AFAIK TW use PSAI an old engine for music, which is inaccessible to modders. So, most modders use the FMOD sound system to implement music. As I know very little about this, I suggest you look at this thread https://forums.taleworlds.com/index.php?threads/modding-sound-music.433302/post-9561243
The other alternative, which is also above my pay grade is to implement a separate sound engine, as Ster has done for KOA.
Thanks for the instruction! I'll do it.You should submit this as a bug report, not a suggestion, here: https://forums.taleworlds.com/index.php?forums/bug-crash-reports.784/
with the id of an uploaded crash report.