consider very dark walls like navy, dark grey, rich caramel or deep rust colours with eaves and fascias white, downpipes same as walls and gutters a mid range colour to match the dark walls (btw some new paints are supposed to have heat reflecting qualities even in the darker colours)

We have just completed our renovation of 1961 kitchen, I used white on white as one south (dark side) of the house. I just love it. I have blossom white cabinets with organic white caesarstone bench top with marble tiles splash back except in fire place where the stove top is caesarstone same as bench for easy cleaning, you are so lucky to have north facing, our bedroom has the north facing light (such a waste) but I do love my new renovation that included the kitchen update and opening up the living dining, just have to wait 16 weeks for the new lounge though (such a long wait)

Exactly the same tones as mine except i lifted it with a stainless steel col glass splashback and s/steel handles. I can change my accessories to suit the season even . clean and lovely as dark col bench tops look cluttered to me.Infact last week we even replaced the two downlights with 2 smoked glass pendents over the sink ( like yours) and they look great. Glad you are happier with your chosen result.

Go back to the builder first it should be still under warranty and see what he says. It shouldn’t be coming up but depends on how you treat it when cleaning, The rubber is silicon and should be a mould resistant type, but I am surpised it is around grate, Post a picture