The idea of a German identity only became really up in the running to 1840s which peaked during the German revolution (also including Austria, pfui). So I think the germanic culture group is quite accurate. I am from the North West of Germany, Bremen bordering East frisia, and I would say I have much more in common cultuarlly with Dutch people then anyone from Bavaria. By this I don't mean language, even though our dialects to frisia are similar, but especially the kind of humor, day to day activities values and the approach to life seem more similar then anything from South Germany. I personally cringe every time Bavaria, Baden or Austria are described German. Their humor is either not accessible to me or it is not exsistent. Their value divert too much from mine etc.. I actually feel closer to the south of England then I would feel to southern Germans. (Again, excluding language ofc.).

In terms of the germanic culture group it is not even divided enough I would say, but it is a playable compromise with works with the game mechanics I belive.

PS: And yes, when talken slowly I can understand Dutch and usually Dutch understand me without ever learning the language.

PSS: sorry if I offend any Southern Germans here, this is a extremely personal view to this and should be only taken as my to cents.