What, Prussian language?? I think, it was just German. . .OK, Berlin sounds a bit different than Munich, haha, but then the Bavarians would rather say, they speak Bavarian(Bayrisch), than the Prussians speaking Prussian or Preussisch or what not. Berlinerisch, well, yes, some. ;-)
But who knows . . maybe there was a special language, but surely not in the high ranks, except that they spoke French for longer, when Aristocrates, alors. Was it before all that? Must have been.
You see, age does not stop one from learning.
Anyhow, where did you get this from? Sounds interesting nevertheless!
(but I am just a lower saxon, those who married into the british empire at times)
And Kala, I started with Chinese, then a bit Korean, and then Japan had me, but not my very well language capabilities. But the cultural path was perfect.