Add wall Moulding

Add Wood Material as TV backdrop, recesed shelves with LED lights and floating console table.
Make sure the backdrop framing all the way into the sloped window.

I think a deep blue or green would go well this your orangey/brown wood tones and yellow throw blankets in the lounge. I would take it over the fireplace and across the tv wall as well, so it looks all of a piece.

I did this with my own bedroom and even took it up the ceiling to make my bed feel recessed into the wall.

For the stair wall, I to would add some wood panelling. Some simple tongue and groove 2/3rds up the wall painted in a warm deep beige colour just slightly contrasting the white you already have. I think the wall just feels a little featureless and the artwork on the staircase overwhelms the space, they’d be better placed in the lounge where you have an expanse of white blank wall.

Devyra , mind giving an ai mockup of the wood slats as tv back