Hey-ho,
as I installed GUAM v6 over my German version of M2TW I had to recognize that the soldiers of certain factions, namely Scotland, Russia, Poland, Hungary and Denmark, remained silent during battle and on strat map. This was due to certain accents of those factions voice files in the English version of M2TW not being available for the German version.
The solution was quite easy as I figured out that there was a mapping mismatch between the voice files used in the German version of the game and the English ones including certain accents. Then I simply changed the mapping from the voice files of the above mentioned factions to the voice files of the English units, which are definitely available in the German version. To cut it short: Scottish, Russian, Polish, Hungarian and Danish soldiers now sound like the English. Probably not perfect, but it works.
Instructions:
Before taking the steps below, make backup copies of all mentioned files in your retrofit folder! For your own safety...
Simply copy over the corresponding files in ..\retrofit\data with those in the attached .zip-archive, delete the files events.dat and events.idx in folder ..\retrofit\data\sounds, start the game and go crack some skulls. Ingame o'course!