IIRC, in the boardgame they are
called 'Mountain' troops but are not really, this is why they are labelled as regular infantry. May be he just made the same in the PC game.
Checking actual OOB for the era in the Balkans, those units were actually not Mountain troops (as could be said of French Chasseurs Alpins, Italian Alpinis or the German Gebirgsjägers)
