If I had one wish it would be pretty much that. I realy hate the zero feedback in nwn, like e.g. your own health gets low and such. Modern games have stuff like that by default so to speak. I never even dared to ask for this, as I expected this not even possible (for whatever reason).
I think it would not be that difficult. Imagine you already have blue flashing effect for some frozen/dom status effects so you could just change that to a beacon effect that's already ingame. Apart from knockdown/death they all probably act as a debuff effect.