This is only my opinion, but that does not look good at all. I'd redo this (move the casing in to have a small reveal), or at a minimum extend the sill length to compensate for the large reveal. That's the most glaring issue to me.

If the issue was only the reveal, how would you feel about it?

The sill should be past the casing

The sill should protrude on the sides the same distance it is proud of the front face of the trim, imo. Hard to tell, but the trim should also overlap the actual frame of the window at an consistent dimension, like say an 1/4". your photos appear to show an inconsistency. Not sure what "reveal" you are referring to.

When you say reveal do you mean trim or casing?
Check out the link..
Link https://www.thisoldhouse.com/how-to/window-trim-rules-thumb

By trim, I mean casing, and when I say sill I mean the stool.

By reveal that bit of the window (not sure what it is called - the jam?) that the casing is not covering. In a lot of diagrams online this reveal is very narrow, 3/8". We have around 3/4" but a bit more in some places. As Moss Wong observed: It is not always consistent.

Does that make sense? Sorry for any confusion.

Thanks for the feedback. I'm trying to decide what, if anything, to do at this point. Team 2 ran this all past my husband before putting it up, and he OK'ed. I think what might have happened is that they needed the casing out to a certain point (to cover issues with our very old plaster walls, there's quite a ragged edge between the window and wall when you pry the casing off and look behind it) but were reluctant to go from 4.5" to 5.5" casing given that in one room (the pink one I photographed) the top of the window is so close to the ceiling and the verdict was to keep things consistent. But I am not 100 percent certain what went into the conversation.

At this point, changing it up further is on me and I don't want to frustrate anyone by walking back things my husband authorized or asked them to do, so I'm trying to work out which aspects of this are serious and which are not.

Are these new construction or retrofit windows? (Retro fit windows fit inside what is left of old windows). The "reveal" none the less should be consistent with new windows which should have been install plumb and square, and the casing to follow. The sill looks like they were existing to be retained. Also, window installers don't usually patch plaster or drywall (need another sub) so there lies the problem.

If it were me, I would take the trim down, fix the plaster and then trim "normally". Otherwise I would go crazy looking at it the rest of time I lived there. That said, if the interior sill/stool was extended to be in proportiion to the rest of the trim,I think it would look ok and 90% of people would not notice.

Are you hanging a curtain? Then leave it alone so there is no conflict - ask though if they can fix the stool...

It looks to me like they installed windows that were too small for the size of the opening, and are now trying to cover all the "gaps" with casings. In older homes, you really do need custom windows.

Since you already have the windows, I'd try painting the trim white on one window and see if it helps things "blend together." The things you are noticing won't be so obvious then.

These are replacement windows for an old rowhouse (1880s). The company who did the installation does only custom windows, so they built the windows to measurements that they took onsite. How they take those measurements, and what bearing our old walls and previous window installations might have had on them (if anything), I don't know. These are not the first double-hung windows to go in.

I didn't think to measure the old trim or take any pictures that are going to be very helpful. We had this same company put in a custom door and resize a window a few years ago, and it all went perfectly, so I just counted on things rolling out the same way this time. That was a mistake; if I'd tried to understand something about windows before now and mapped out what needed to happen, this all would have gone a lot better.

I do have this old real estate listing photo of the same room from 6 years ago. The original trim was quite wide, at least 3"; I notice that the old casing in the photo is about as close to the ceiling as that new 4.5" casing is. So the 4.5" might not be quite as excessive at it sounds.

So the large casing is OK, I think, unless I'm missing something. I think where the issue came in is that the gentleman who measured with us for the current redo [there was a previous attempt that went badly] ordered larger casing than they had previously installed, but didn't order any replacement of stool. He thought that the casing to be ordered would be less wide than the stool that they had already installed. But that assumed the casing would go up with a small reveal. It didn't, and with a reveal 3/4" and 1", the outer edge of the casing falls about where the stool ends (and are a little past it in one case). The installation team had no instruction to replace the stool as needed. Meanwhile, my husband didn't see the problem - he saw that the more egregious errors from an earlier try were gone [there had been some trim narrower than the original put up, which left even larger reveals than what we have now, plus a gap between the wall and window] and rejoiced.

At least, this is what I have pieced together from what I know.

If I ask the window company to replace just the stool, is that a relatively simple fix that everyone will like to hear? Can they just remove the apron and stool? Or would they have to take most of the casing off and start over?

You should take a level and document the installation. See if it is level and plumb. There can be some deviation, but how much? New windows need to be installed that way. In your photos, they look wavy gravy to me and inconsistent in regards to the reveal. The casing doesn't appear to be straight either. If the stool and apron are also to be new, I find that unacceptable.

I would extend the beyond the casing as mentioned and would increase the thickness to 5/4, The apron seems odd , they should have metered the ends. customs sized Windows is the norm,?everyone does it.

Were they full Framed windows or inserts?

I believe they are framed windows; the windows are set in a big metal frame that arrived as a whole unit and went into the wall.

It looks to me, based on what I am getting from the level, (putting it against the sash, sides and top of the metal frame set in the wall, etc) that the windows are level and plumb. When I look at the carpentry, the distence between the inside edge metal window frame and the inside edge of jam, as well as the reveals between the jam and the casing, all wander a bit. Most of the differences are 1/8" to 1/4". I think that is why everything looks a bit wavy.

How far off acceptable margin or error is that for carpentry mounted to old walls?

Good news is the windows sound like they were properly leveled and square. Sounds like the workmanship of the casing and trim is in question. The trim should track with the window frame and be relatively level and plumb at least relative to sash. If the deviations of up to 1/4" occur at the same piece of casing, for example, even accounting for unevenness of wall (which can cause the trim to be distorted) it does sound like poor workmanship. It is much easier to see how bad this is if you take a sample window and document all the variations side by side, corner to corner. Perhaps a carpenter can chime in here and give you an opinion, but the deviations do sound excessive. If it was a DIY job, then that's another story.