I designed this room in a Mid-century modern style by adding more wooden elements all throughout the room.

Wooden elements can be found in the railing of the stairs and in the coverings of the radiators. When picking the color of the wood I tried to go with one shade darker than the color of the existing tiles.

Also, all cabinets in this room should be painted black, while leaving the drawers wooden, and the door that leads to the kitchen should be painted black. The railing is also imagined to have some metal parts so the black in the railing can match with the black cabinets around the room.

You can keep your prints, in my opinion, they add a lot of character, just change the places of them.
Some details should be brass or copper, like the hanging wall lamps as well as the hand hooks on the cabins with drawers.

The curtains I added are optional, if you don't want curtains then I suggest you change the window sun shutters to wooden ones or get ones in brown color, similar to wooden details in the room.

I also suggest that you change the brackets on the wall shelf unit in the living room that you already have installed, from silver to all black metal brackets, details like that would really make the colors of the room more cohesive. (can be seen in an image of the living room I provided).