I gues because the exe uses outside files it is working independantly with US version. And everything so far is in English. However there is a price to pay... You won't be able to use cards that were locked in German version... Just compare the sizes.
The best case scenario would be to use Russian version which has everything unlocked (some cards were considered not suitble for fragile non-russian minds
). Of course it has to be fixed - otherwise it will look for Russian cd...