I doubt it. the builder probably had codes to follow so the air system would work optimally. One quick fix is to paint the vents the color of the wall.

You need to contact a licensed HVAC contractor and discuss the possibilities of moving the RA duct and the grills........however, it will need to be calculated out as to what the possible solutions might be based on the parameters of the system size, the required RA flow and the location in relation to the supply points and the air handler system location.............it's not just something that you move on a whim.............and yes it's going to be expensive.

Unlikely - it should have been painted the wall color, that is why it is popping out visually.

That is a good idea, but you could also get a very large painting to cover almost the entire area. Truthfully it doesn't look that bad. I am sure you can move it. It just might have to go on the stair wall or hopefully on the bottom of either wall.

That is a high/low cold air return. They pull stale air from the room and recirculate it through the furnace (or air conditioner) to refresh the hot or cold air of the house. You will only see a few, if that many, in a house. These are interconnected and in a central location for a reason. I imagine the thermostat is somewhere nearby? Moving them would require a redesign of the air handling system. doable, but not cheap. No guarantees that what replaces them is any prettier or in a better location...sometimes function is more important than form.... And I know this doesn't help...sorry.

That would be good, would it show less if the wall/vent were painted a darker color?

Moving the vent would probably be very expensive since the contractors would have to redirect the ducts and that would involve breaking into the drywall.....I think painting the top and bottom grills is the easiest solution

S. Thomas...Thank You, fantastic detailed plan of attack.
Ironwood..thank you, it does help!
I

Ironwood...I do know that ;) I won't be covering it!

Cherc..I want to make sure folks don't heed advice that can send them over a cliff.