We had a house with a timber ceiling - it is a tricky decision. If it is a cheap display home build perhaps cover it, but if the quality is good it is a much harder decision. I think it looks good now and could be made very interesting. Also that look is "back". Make sure your lighting is very good and the heaviness will dissappear somewhat. The floor is lovely.

I really like the ceiling, as others said it gives it atmosphere and frames the view. When you say pine, I'm thinking you mean the finest of all the pines - Oregon which is fine grained and a warm honey colour. I have a cathedral ceiling and I would gladly swap my bland white faux Hamptons look with you any day! I would look at a large rug for the floor - if the budget is small, find a carpet that you like and get it edged as a rug - my favourite hack. I agree to bring in some black in the curtain rods and swap out al that cream/yellow paint for a neutral white. Your kitchen reminds me of mine circa 1998. Change the splash back to something neutral. Even white painted glass or a white textured or interestingly shaped tile. Swap out your bar stools for timber and introduce some timber elements in the kitchen to match the roof. Think chopping boards,, timber bowl for fruit, utensil holders, pot plants. Paint the walls white as well. All the creams in the world won't help the ceiling look better. you need to work with it not against it. Good luck and keep us up to date!

I agree with both your painter and your Google result. The issue is something that has soaked into the surface of the old wall, particularly as you had an odd result when cleaning. You can’t expect the painter to sand and paint as part of the original job but they may be able to offer advice and action if you’re prepared to pay them. If you want to DIY I’d be sanding the wall and trying some stain locker undercoat.

The best way to cover dark is to use a grey tinted primer first. Talk to a paint specialist. Dulux on line may help