The cataract idea might not go down well with Ady mind as even with the limited colour of his revised ESB hologram you can still see the Sitheye colour.
As for the dark thone room, there will be times when the room is much lighter than it was (if the sun is breaking through one side as in your mockup it will swing around eventually, actually if you timed it right having the sun come around when Vader turns back to the light might add some impact).
Very rough it's early in the morning :
It would as you say give some drama to the saber and Force Lightning and hide some of the flimsy nature of the set.