> The recently cleaned ceiling can be seen here: no wiring or
> light bulbs, though.
The panel is a depiction of a possible electrical circuit, it doen not mean that the system was actually there in that place. It may not exist or be buried somewhere else or destroyed/became incomplete, or it was indeed a story (handed down) that contained a blueprint for such a device and put on the wall to remember it. It is also possible that the Egyptians did not really understand it!
ps. Did you understand me about the animation? I do not know if it is in the literature of egyptology, i looked at the front of the Temple and saw it, did you see it? Do you know anything about it?