Jamie, some people have used the sides of plastic milk cartons for the "pebbled" glass in their models' windows; the plastic is frosted, and textured, and at that scale about the right "pebbling" for the window panes. That would be easy to cut to shape. And since the Brachacki (Original and Altered) had all of the panes in all of the windows pebbled, all you would need to do is cut the shapes to fit the whole window and it should look just like the real prop (especially when photographed up close).
I hope this is helpful.
Dino.