If you are looking to keep the "period" look, then I say no. My place is from 1916 & had a gross 1980's reno. I ripped out all the ugly vinyl floor & cheap Sears sink & went with a black hex floor, white subway, dark grey grout on both. Toilet & tub were original, but I got an old "Standard" wall mount sink with chrome legs & towel bars & an antique medicine chest, light fixtures & glass shelving & towel bar off Ebay. My total job...about $5k. Help my tile guy is my neighbor, but those 10, 15, 20k bathrooms were out of the question.

Bring the window down to meet the cupboard. Really lefty47 was right about not drawing attention to it. It is a source of light ,,, so no need to clutter it up. But if you took the colour out and painted the top of the cupbard to match the wall it ceases to draw attention to itself. Just because it is a horizontal space does not meant it needs something put on it. Note- With the cupboard being white, it also draws attention to itself … perhaps take that to the wall colour too and lift the pendant a smidge. So your pendant is the feature there. The cupboard … do yo need it? One way to remove what you are calling dead space is to get rid of the cupboard.

I would not recommend glossy tiles in a bathroom. We have 24" polished porcelain throughout our house, and... we also have a pool. Although I love our tiles, I have to be super careful coming inside. If I am at all damp, walking on the tiles is tricky. Yes, they are easy to keep clean, but so are most tiles. For my master bath, I went with tiles that had a high COF (Coefficient of Friction). I've had my fill of slippery bathroom floors, and wanted something that I didn't have to slide a towel around on. I love them! I can step out of the shower, and have as much grip on the floor, as if I had stepped onto a mat. :)

Personally , I wouldn't use that wallpaper -- it doesn't suit the apartment style IMO . I assume she wanted to add some focus and colour , but to me it doesn't work . To make it work ( or at least not 'jar' ) if she does insist on the wallpaper , pick out the burgundy or red of the wattle flower ( or whatever it is ) , and do a wall opposite it in that exact same shade , or maybe the kitchen area if you have good masking skills . The animal skin rugs look great , but the couch is 'lost' -- add cushions in the same red or burgundy as the wall , or go even brighter red or burgundy . Rest of the walls can be left as they are ( depending on wall condition ) or any similar neutral ( aka bland ) grey or cream , or possibly even a light steel blue .