Naming and language I get. I don't care as much as others but I understand as we are building up cultures, those cultures need to be stuck to. But poses are different. I understand the way people carry themselves does also speak to culture. BUT we are talking about taking a written medium and making it visual. What people have imagined in their own heads for the 'behind the scenes' moments will now be presented physically. The moments that aren't even in the books but people have imagined will now be shown. And they might clash. Which is frankly okay. Cos everyone's versions are still true. Including those in people's mind, those in the books and those in the show. But they have to physically show them.
Maybe Galadriel never sits like this in any of the scenes we have 'seen' in the book. But to say she has never once sat like this in her fictitious life is frankly an unknown.
I really don't think that one entirely out of context image (which is like a promo shot not from a scene in the show proper) really tells us too much about their interpretation of Galadriel.
It's easier to pick holes than to like things.