1) How different is modern German from the language circa the eighteenth century? It looks to me like they were speaking New High German, which is apparently more or less the same as Standard German nowadays, but my own facility with the language ends with one proverb and one alarming speech about having a grenade (don’t ask), so it’s all
Greek German to me. My guess would be that it differs in much the same way as eighteenth-century English does, i.e. more in phrasing and word choice than anything else, but I’d like to know for sure.
2) Once I’ve sorted that out, I will need someone to do small amounts (i.e. a few sentences) of translation work for me, either into the modern language or into New High German, if that’s noticeably different. If you have fluency with either of these, or know someone who does, please drop me a line.
(You would be justified in asking why I should contemplate translating into an archaic dialect of German when I haven’t been writing these novels in equally period English. The answer is, because I can. Assuming I can find a translator, of course.)