I feel a bit embarrassed solving my own thread but oh well. If you want to change your campaign music go to your KGCM data/world/maps/base folder, then open descr_sounds_music_types file. You'll see five different music types, just copy and paste your faction and regions, and then paste them to the music type that you want. Also remember to list your faction at the bottom of the music type section labeled "factions". Finally erase your faction and regions from the old music type to avoid conflicting commands. No new campaign required!
. (Im not sure if you need to but i also deleted the map.rwm file, dont worry it'll regenerate when you start the game).