How funny. I just renovated (on a budget) my small kitchen and added exactly the slate look in tiles you have, though they are in fact porcelain. And I placed them throughout the house for continuity. The tiler asked if I was after a retro hippy look but it doesn't look like that at all. My cupboards were the same colour as yours and I utilised the bones of the kitchen and had the doors and Benchtops changed only. I also have plenty of light in the kitchen but chose white doors and as I was on a budget I chose granite look Benchtops, they are very serviceable and it looks great. The blue backsplash was the colour lift and here you could choose any colour to your liking. Basically the kitchen ended up with white cupboards and appliances other than cooktop, with the stainless cooktop and coloured splash back being the focal point. The paint colour are: whisper white walls, integra splashback, white ceiling and for increased contrast I used the same white above the splashback on the rear wall. I would consider painting out the brick but leaving the texture.

Have you priced having the whole lot re waterproofed and tiled? You are already doing the hardest section, it may not be that much more to do the lot. Otherwise agree with above match to the white tiles in the rest of the bathroom. But it will always look like a repair.

In an apartment you need to check before you add floating floors. Some buildings have regulations to assist with noise control. If you keep the tiles, do they have the same under tones as the paint you’re considering using?- a clash between a cool and warm white will always look odd.