I love the effect. I remember how many shots the photopass gunner took when my wife and I did this. They took so much time getting the shot perfect, it struck me as the sort of thing that might show up on the photopass screen when you go look them up. Since the lantern's a known quantity for every shot it would be possible to process the effect with an algorithm automatically.
If you don't mind me riding your coat tail, I think I'll try the effect myself for the print we're doing of this same shot.
Mask it and us the dodge tool to darken it. What I would actually like to try is to grab a bunch of the 'floating' lanterns, mix them up, and drop them down into the background to fill dead areas like in front of the door to the toilet.