Not really. To be honest, the last few dreams I had (quite a long time ago, actually) were so upsetting that I'd rather not remember any dreams at all, whether featuring a language, or not... Although I could swear I read somewhere that during sleep the verbal part of our brain turns off, or something like that, making it impossible for you to see real written language... Oh, yeah... Or rather, I might be completely making this up, but I think that's one of the signs for people who can have lucid dreams... Yeah, this page goes more into detail: https://www.quora.com/Why-cant-you-r...-a-lucid-dream

On the topic of Facebook, well, I'm not a member (although I am on the local competitor)... But can't you, maybe, add German as a language that you speak, and it would get that it doesn't have to translate it for you? Or would that be too suspicious? I mean, for people who visit your page.

If all else fails, and, well, if you're prepared to go this far, I'm sure you could set your whole Facebook to German... although I guess that would mean that your English friends' posts would get translated to German... Yeah, the first idea first, then this maybe as an extra. I don't know if I've mentioned it in this thread, but I've got my social networks, and Google, in Polish (so in addition it looks first for results in Polish, no matter if I actually searched in English, but at least Polish Wikipedia almost never disappoints).