Here is what I think happened and I don't think it's a result of you trying to put this back together. I think some time before you bought the house, the dim8 failed and the rope lights would not turn off or dim. The easy fix was to move the wire that was supposed to be on terminal 6 (ropes) and move it to terminal 5 (back lights). That way when you turn down the back lights, the ropes turn down with it. The back lights are working so they must be getting their power from the dim4 on terminal 1 or terminal 5 on the dim8 (I suspect 1). The red used to be on terminal 5 and the black from 5 was on 6.
That red wire which is supposed to be on terminal 5 goes to a "incandescent" light someplace.
1. Is there a light fixture in the pocket for the projector?
2. Is there a light of some sort outside of the entrance to the theater that you wish you could control from the TP? It may even be on a switch but may be getting it's power from that red wire that is always hot.
3. Is there a media storage cabinet with a light in it. How else would you find your cd's and dvd's in the dark.
4. The equipment room. That's probably on a switch but you never know.
5. Any plugs in the middle of the floor near the seating that a lamp may have been plugged into.
The fact that it's associated with the "back lights" and not the "front lights" leads me to think that it's also in the back of the room. Look for signs on the carpet indicating a large furniture item was there perhaps a lighted hutch.
After we get the new dim8 in place and run network analyzer again to make sure all the cresnet errors are gone, it would be interesting to re-try hooking up the jandy spa controls. If you remember, we were trying to control and monitor it from the TP1000's They are on the cresnet which at the time was riddled with errors because of the dim8.
You better figure out where that red wire goes before I make you fly me down there and find it