I have tried the thing with type XXI in the language file of CAOD, it doesn't work, and for what I can tell, all is related to language output only.
What works but doesn't change anything is: I have taken all sound files from DOS version (which all work perfectly in the game) and transfer them to CAOD, it works but - very unfortunately - it doesn't change the 'fading-out' of the sound which is terrible in a sub sim. If only there were no sound problems, CAOD would be a very nice game, it's to despair..
Be sure to revert the changes, you don't want to mess-up your game...