Thank you very much!

Neither one of your rugs is large enough, and your floors are so interesting that I think they'd look good left bare. Sofa rug should slip under the front 1/3 and extend past the ends by a foot or more. Dining rug should be larger 4-6 feet larger than the table top so chairs don't "fall off" it. If you leave the floors bare, you could try an accent rug, like a hide or flokati, just under the coffee table. Your sofa seems to be blocking a door and the view. The buffet is too large for its wall. What is behind the table? Is it an open kitchen, a wall or what? You've only shown us two walls, so we are not informed well enough to make totally relevant suggestions. Please post some more photos.

Can you change the coffee table? I'd like to see something more sophisticated to echo your lovely chandelier. Since you can't paint the walls, you might consider hanging an interesting piece of fabric as a large piece of art - you could stretch it over a frame like a canvas. A natural weaving might be neat there. There is also removable wallpaper, though it's not cheap.

Thank you for your replies and opinions. I send you some more photos to understand better. The buffet can be move somewhere else you think? The sofa table has to stay as it is new
From the left of the dining table you can find our office.
I upload some more photos!

Might be nice to try Scandinavian prints/art to set the tone in here.

Scandinavian