CS is screwy beyond belief sometimes. The variety of light spells have different magnitude and duration values, but the effect is the same - "Light". Okay, so where does that come from? After a little investigation we find it in WorldObjects\Light\SpellILightSpellMedium.

The good news is you can change the color from radioactive green to something more like a torch, yellow/orange or whatever. Bad news is you get one light color and one only. Clone the SpellILightSpellMedium to SpellILightSpellOrange or something, clone again so you have red yellow blue purple, now we can make half a dozen different light spells so the player can cast different colors depending on his mood!

Uh, nope, sorry, there's a connection SOMEWHERE between the effect and the SpellILightSpellMedium, but I'll be hanged if I can find it. This apparently doesn't use any kind of script so it should be ridiculously simple, but near as I can tell there's no way to add a new effect to the list of choices when creating a new spell.