So, some words form perspecitve of developer here:
We decided to choose a more modern english, because we want that people understand the dialogues, and not only native english speakers, but also non native english speakers. Not every country will get his own translation.
And we want to have some impact with our language on the player, he should feel into the game, and if we use an old uncommon historic language here, the connection would be lost, and the player would not feel this kind of immersion, he would feel more like a kind of guest in the game.
Historic correct would be old czech, old german and hungarian, and you would not find enough good voiceactors to do this job. So the language is a compromise here.
But... I ask myself, if someone get thown out of the immersive game by strong language, is beeping it out really more immersive?