I think I have something that might work for you because it worked for me.
Step 1: put the background into the script.
Step 2: place the character where you need them.
Step 3: create an overlay of that same background and change the opacity to around 40% or more (you can try changing to different opacities and see what suits you best), and position the overlay to match the background.
Step 4: create another overlay like this, where you’ve cut off the windows: 
, and keep it opaque (set the opacity to 100%).
And that should do the trick.
I don’t know if you’ve already figured it out, but this is just how I do it and it seems to work.