Love the sofa. I would get upholstered chairs rather than more leather. I think the Nina chair would complement the sofa but in a fabric. The Sven is too contemporary for the sofa

I would add a rug parallel to your desk and make sure it is a little larger than the length of your desk. I found this size guide which might help: https://www.rugandhome.com/blogs/decorating-guide/17369272-rugs-101-selecting-a-rug-size

Warning: (learning from just painting Grey in my living room that has loads of windows and light) Most Grey colors turn out much darker looking once you paint them on all the walls. We spent $2,000 to change the grey in our livingroom to a lighter grey because the first one turned out too dark and that was a grey that was much lighter than any you have choosen. I had even gotten a sample and painted one wall to test the color but when the walls all reflect off each other it gets way darker! I would test Beacon Grey or Breath of Fresh Air. We ended up using SW 7071 Grey Screen You can see in this photo how much darker it can get depending on the shadows and lighting. Here it is in the day light: During the day it is almost baby blue but at night it is VERY grey.

Is this space the walkthrough path between a hallway and the kitchen/living room? If so my recommendation for a client woul prolly be: -Murphy style desk along the back wall where you have the tape. It houses all the art supplies while still being easy to fold up & close should you be entertaining or need to quickly clean up. -Not sure what style your current LR furniture is but if you like it & want to maintain that cohesive nature then I’d recommend checking out PB kids/teen for some chair ideas that they’d enjoy and can still look pulled together whenever you want it function adult space. -For rugs I prefer Dash & Albert or Shaw for families with kids n pets. The PET line (made from recycled plastic) from D&A is as soft as wool but easily cleaned up with soap n water. The other indoor/outdoor models allow bleaching should it become necessary due to spilled paint, etc.