May I suggest contacting the interior designer to request information on the tiles?

Just get the grout and glass sealed at the end and all will be perfect. You will only need to seal the shower area. From memory I think I used a company called endurosheild? There are a couple of shades of white tiles, worth matching your dark tile and vanity to get the right shade but that's easier because the tile shop will help you. Will still look white, just not too white. I'm using black button tiles as a backsplash for the vanity so I also needed to use a slightly tinted white.

it's never perfect and always involves a balance/compromise to achieve the less noticeable outcome - it's the decision with the convergence lines as to whether the base run is cut or the wall. That the wall run is cut it accentuates the pool fall more - if it was the other way around, in that the wall run comes down to a straight/horizontal line and the base is cut into that line the angle would not be as noticeable......you can fix it, and in this case arguably due to the window perspective looking straight on it's a justified request - adding water won't improve/soften the end result dramatically in this case IMO....that main thing is that it's been prep'd straight which it looks like it has been - this is only cosmetic remedial, which whilst yes will cost the contractor, you have to live with the end result so it's worth the (hard) conversation......good luck!

I’d go with timber or cork. Cork is great in a kitchen. Easy on your feet and joints and things are much less likely to break if you drop them. Especially as you age, tiles cause fatigue if you are standing in the kitchen for too long. Cork is now available in lots of different colours and styles including charcoals and greys that might compliment your slate. It’s not all 80s orange. Of course timber can look great too. Just make sure it’s ok for kitchen use.