I think I updated all the lights but once it goes on to test server or live, if you spot one I missed, let me know with a /bug report. (4 quality levels x all the lights in game = lots of fiddly files).
Non-light sources will say "this ornamental light fixture gives off only a gentle glow" and true light sources that really do give off light will say "a warm light shines brightly from this finely crafted fixture".
Note: all the lights still have a nice glow associated with them, however this isn't the same as actually lighting up the room around them. Even the non-lights do still look lit, and warm, they just don't make nearby objects brighter. A nice combination of both types of lighting should make for a bright enough room, with lots of pretty features but not too much lag.
This most likely won't make it to test server till next month, and will probably go live with Game Update 36.