Hi!

When searchlights are connected to a network, they both output and receive rotation and angle data, which means that searchlights interfere with these properties for other search lights on the circuit network, as all the signals are additive. Is this intended?

Yes, you'll have to build a "diode" from decider or arithmetic combinators if you need to isolate signals.

It's the best solution I have for now, but I'm open to suggestions for the future, when my life settles down (I might allow setting the signal outputs like how roboports work, for example).

No worries!

My personal ideal would be that the settings on the light itself are treated as an offset from the network signal. So the light would add it, but not send it back out to the network. For example, I would use a constant combinator to set all lights to 90 angle and 0 rotation, but if I have one light I want pointed another direction I can put 90 on that light and it rotates 90 relative to the other lights.

Barring that, I'd rather have the lights not put out a signal at all and have the network override any settings on the light itself. The ability to set outputs like a roboport would be a nice bonus feature on top of that.