We have the black mirror splashback. We love it and it soooo easy to clean

I feel it's too heavy looking for your room. You say it's a very large room, so you don't need it to make the room feel larger. Perhaps look for a picture/painting.

An entire wall of built-in cabinets and hooks and cubbies for your crafting stuff (and perhaps filing-type stuff and printer for the office). Take a good look at what you have and think about how best to organize and store it and what could be displayed to be pretty and what should be hidden behind curtains or doors. A fold down ironing board on a wall or back of a door somewhere would be great. A nice desk and filing cabinet for the office side... or perhaps a great big table in the middle under the window, wide enough to function for both of you facing each other? A nice curtain rod would make a big difference too. Preferably just about floor to ceiling. I'd put a splash of colour on the walls and keep the curtains simple, but you could go vice-versa too. Something like this: [https://www.houzz.co.nz/photos/modern-bungalow-phvw-vp~4999540[(https://www.houzz.co.nz/photos/modern-bungalow-phvw-vp~4999540)

Your client putting trust in you was the right decision! amazing transformations! Love the natural light in particular as thats a great spot for a post gym pump flex for a good selfie!