Is the room in question a powder room or a bathroom where someone would be referencing the mirror for makeup application? If the former it might work well.

Your home is gorgeous. I like the idea of a bathroom with dark walls to compliment the rest of your home. Were you asking if green or brown was better? Did you use a green or brown paint you like in a nearby room? I wondered if you could use a dark brown on the bottom half to show off the gorgeous white pedistal sink, and green on the top half. Sometimes "and" is more fun than or, especially if both colors are already present in an adjoining space. I like the idea of keeping some pure white bright elements like the sink, toilet, sheers, and lamp shade for contrast and drama. Let us know what you think about ideas shared with you.

With 1750 in CT, I would go with historic colors… like shown here:

Historic New England paint colors

Do you have pics of the bathroom in question? The pics in the OP seem to be inspo pics since they are from different places that are not showing as in Ct. What kind of light do you get?

None of your photos are of your home.

English Brown or Green seems like a good style for an older home provided a high light level is not required for the room.

I love the historical collection from Ben Moore - it never does me wrong, I'd start there for some color inspiration (I have an old house and always like lots of white in the baths bc it seems fresh & clean but everyeone is different)