Love the coffered ceiling. I've done only a couple of those in my many years as a carpenter. A lot more raised panel walls and wainscoting and some wrapped beams. Always a fan of great woodworking.
Getting back to the stenciling, I think there is more life to stencils than paper. I'm sure the paper manufacturers have just about done all the classic Victorian patterns but with stenciling you can be almost sure your job will be unique and no matching of paper at the corners required.
I had a homeowner do something very similar to this in West L.A.
After getting the colors and pattern up we went over it with a thin umber glaze to "age" it a bit. I do the same to cheap framed prints. Makes them look like the old masters (if you don't know siht, like me).