The key to this setup is whether the viewing angle for the TV works. For us this resulted in a slightly higher than normal viewing height, but one which was acceptable. This depends on: 1. Eye height of whoever will be sitting on your sofa facing the TV 2. Height of the back of the seating facing your sofa 3. Distances between viewer and chair and between chair and TV 4. Size of your TV The above will determine what height to set your TV so that the bottom of the TV is visible past the chair. There's a lot to think about actually. E.g. (a) chairbacks too tall will lead to the TV placement being too high, which would make it uncomfortable to see the top of the screen. So don't choose high wingback chesterfields. (b) Assuming your viewing height is above the chairback height, then the greater the distance from the chairback to the TV, the lower the TV can go, which usually would be closer to the ideal viewing height (c) shorter people will have different viewing heights, so what works for you might not work for others, or might result in the TV not being fully visible if laying down, for example So you need to think carefully what works for your room and your furniture plus TV

Urgh, I had the same thing in my last house and I was forever repainting it! (And that was with a kitchen paint) What was most annoying is that I had wanted a much deeper upstand ie going up under the window cill, and the kitchen designers told me I was basically nuts and that’s not what I should get. I shouldn’t have listened to them. It’s fine elsewhere but the sink (and I didn’t have a bowl in it, ha ha) was a mare! You could get another section of the upstand cut to fit into the space. Or some heavy duty wall paint designed for wet areas. Or subtle mosaics perhaps

Now everyone is installing soundproof walls. Thanks to these walls, the sound penetrates less into your apartment. The other day I downloaded two sound measurement apps that my neighbour suggested. The first was the decibelpro.app application. I know a lot of hearing problems come from noise. I am amazed that there are such applications that make it possible to measure sound and walls that can be installed in your home for complete sound insulation. I noticed a difference in noise with the sound meter.

Contact some window suppliers and ask them what services they can supply? I suspect you just need a structural engineer. Some window companies may supply this service or put you in touch with someone, or you may prefer independent advice.