You should be able to do that. Can you post or email me screenshots of how you’re doing it? Is your initial setup working OK?
In general you shouldn’t need to invalidates the lights much, although it may help if you’re spawning new lights to then notify anything with a cel-shader component. I’ll have to check it to jog my memory but if I recall correctly it updates the light list frequently. The only thing I’d take note of is that you may want to spawn the lights with no illumination a few seconds early, then turn them on as needed so that there’s no delay in enabling them.
The material side of things is just a material, however you may need to re-initialize the cel shading component for that actor if you’re swapping entire materials, as the reference to the dynamic material will no longer be valid. Just run the method CelShaderComponent->Constructor() after you change out the material. And let me know how you get on with that as I’ve just thought of a possible optimisation: if it doesn’t do it already, consider clearing the Materials array as the first step in the constructor.