Not sure if this is the right place, but I've found out something about both this mod and character select.
It seems that using character select with SCR messes with base character voices as well as custom characters that use those voices. For example: If you select Mario through the player menu then select Luigi or Mr. L from Super Paper Villians through CS, He will end up using Mario's voice. It's even more apparent when character movesets or render96 voices is enabled.
Also, v1.3.1 still breaks this mod. Incredible.