with a lot of handwork u can manage to install it even in the german version.
The file endings in the german version are different from the english version. for example:
in the german version there is a file named airstrip.gad.
Just rename it to airstrip.ead.
And thats for all files, if the endings starts with *.g rename it to *.e then install RA and rename the files back to *.g. and voila u have a german RA Mod
You will loose some german text files which are now english but i think you can live with that.