Coving would go up a lot easier if the walls met adjoining walls and ceilings at 90 degrees, not the 87 degrees and 92 degrees we have here.
I'm reminded of these extracts from 'The Haunting of Hill House' by Shirley Jackson.
No human eye can isolate the unhappy coincidence of line and place which suggests evil in the face of a house, and yet somehow a maniac juxtaposition, a badly turned angle, some chance meeting of roof and sky, turned Hill House into a place of despair...
And later in the book...
"Every angle”—and the doctor gestured toward the doorway—“every angle is slightly wrong. Hugh Cram must have detested other people and their sensible squared-away houses, because he made his house to suit his mind. Angles which you assume are the right angles you are accustomed to, and have every right to expect are true, are actually a fraction of a degree off in one direction or another. I am sure, for instance, that you believe that the stairs you are sitting on are level, because you are not prepared for stairs which are not level—“
Yeah, Hugh Cram built our house I'm certain of it.