Before you get overwhelmed here again with all the expert knowledge, here is the perspective of my modest knowledge.
You had a ready-to-use colored silicate plaster, presumably with a 2 mm grain size, applied. Please correct me if this is not the case.
Problem. The plaster in the bucket was not diluted with water. About one glass of water per bucket. Therefore, the applied ready-made plaster is too thick and harder to smooth. Probably, also, rubbing off was waited on a bit too long, the plaster had already set. And now it looks the way it looks.
A coat of paint naturally covers this. But with a 2mm grain size, not much of the original plaster structure remains. That is the disadvantage of a small grain size. If you paint over it twice, the wall is smooth.
What do you want to do now? A legal dispute is risky. Paint over it? Basically, something like this fades after a few months. Who looks at your window reveal from 10 cm away?
I would leave it as it is. Karma is a bitch. Make a contract with the painter or the construction company that they will paint the house for free in 5 years. Of course, you cover the cost of the materials. Experience shows that in the first years, there are always some stains on the exterior plaster. Because if you have to do it, you have to paint everything. A bit of patching is always visible.