It always strikes me as odd how modern filmmakers making period films are so extremely keen on getting the “visual” side of history and its accompanying mise-en-scene correct for their eras... yet don’t have the slightest regards for language, comportment, attitude, and worldview.
Comportment is particularly off, a lot of times in these historical-based films, with actors who just reek of a modern sensibility, and demonstrate it in the manner in which they walk and talk.
To be honest, if they made the film using authentic dialogue from the day, the educated classes would be so verbose as to become baffling and tiresome to listen to, whereas the lower classes would be virtually unintelligible with their thick accents and use of words that have long since fallen into disuse. Unless their name is Mel Gibson, most Hollywood directors are going to make a compromise so that audiences can actually understand what the characters are saying...