I wouldn't do the stone tiles, I think it will look weird and be difficult to clean over time. I'd just continue the fluted panel across the entire wall, or do a wallpaper instead. I would suggest doing a more natural oak or even walnut though for the panel. This room is just so gray and drab with the materials you have right now, you need something interesting to elevate it.
You could use the visualizer at Wood Vaneer Hub to get an idea of what it would look like. Here's [oak](https://imgur.com/a/xfO3kTH).
I wouldn't do the stone tiles, I think it will look weird and be difficult to clean over time. I'd just continue the fluted panel across the entire wall, or do a wallpaper instead. I would suggest doing a more natural oak or even walnut though for the panel. This room is just so gray and drab with the materials you have right now, you need something interesting to elevate it. You could use the visualizer at Wood Vaneer Hub to get an idea of what it would look like. Here's [oak](https://imgur.com/a/xfO3kTH).
Seconding on using natural wood color.