I just fiddled for a few hours with the Victorian Gift Shop--just the room.
When it loads, I suggest to delete the ceiling for what you want to achieve so you get decent lighting without the forty lights. :) Or nine even.
The below detail image was done with the above mentioned material on the background note, loaded with a snowy (winter) HDRI. There is only one single sublight.The only material I changed otherwise was the glass in the window to the SimpleGlass available in the Superfly folder on materials that came with the program.
It is saved as a png as well. The settings are super basic, see below for results. There is definitely more that could be done, but the background image shows, the glass is there, and there is plenty of light.