Are we making this harder than it should be? One acetate sheet and one interior backround. A lot of glue application area away from the windows. I used contact adhesive with care. Acetate and interior printed sheets were applied before assembly.
Back side.
Side.
On the layout.
I did apply several windows as single pieces. Cut oversized, then held in place dry, applying CA Cyanoacralate (Medium set Super glue) to the edge of the window. The CA has very good capillary action and will suck-in, gluing the window in place. There are different application techniques. Sometimes I place a small drop of CA on a sandwich bag, then dip a small brass wire in the drop and apply a small amount of CA. Applying CA directly from the container can be problematic, requires some practice also.
Note the dark red corners of the acetate windows where the CA was applied. Usually the capillary action doesn't go beyond the edge of the window. It doesn't need adhesive beyond holding it in place. It should set quickly. A building like this has a lot of practice in it. About (40) different applications all done before final assembly.