Fantastic Nbjackso!
Just this evening I was wondering if you had decided to work on the OM map makeover after all and now I see you already started

. This is great news.
I agree about the Italian airbase, it looks bad ass.
I'm willing to help with researching the city names if you'd like. I don't speak german either but I can do the same thing I did for the the sea map labels, i.e. look them up on the interwebs

. Last time I had pretty good luck researching the translations on Wikipedia.de and it was kinda fun.
I checked a few cities at random from your screenshots and all the ones I picked were the same spelling in german. The only one I found that was different is Athens --> Athen. So based on that I'm thinking there shouldn't be that many corrections to make.
Let me know if you need help and I can start working on a list for you.