Tomlong: It's down at the bottom, in the change log. "Version 2 - Now affects NPCs!" Also all that stuff about CLEAN and ASSERT modes, leaving them active for half an hour to make sure far-off NPCs are cleaned up. So yeah, it affects NPCs.

What's up?
Edit: Correction - the soul hunger effect spell references the Magic Effect 'Detect Life', which references the shader 'effectDetectLife'. I don't understand where LifeDetected (the shader) fits in
effectDetectLife is what plays on an actor gaining the Detect Life effect. If you're in third person and you cast a Detect Life spell, it's part of the effect you'll see. (The generic Mysticism spell mesh is most of it, but there are some particles and a momentary skin discoloration that are unique to Detect Life.)
Internally, the Detect Life effect is handled by playing the LifeDetected shader on the screen, playing it on any actors regardless of line-of-sight; like Night Eye, it's handled entirely by the video card (and completely useless to NPCs, since they don't have a monitor to look at). The reference to the LifeDetected effect is hard-coded, and not visible anywhere in TES4Edit, which is why you couldn't find it.

Since the engine directly references the LifeDetected shader, and my Life Detected mod edits it to something other than purple clouds, there's literally no explanation for them appearing other than a different mod adding that effect and, when it sees a Detect Life effect on the player, either playing it as a full-screen shader (which would require OBGE, I think?) or detecting all actors in range and explicitly playing it on them. The only reason I could think of to jump through those hoops is if you want to implement specific, independent detection for living, undead, etc. creatures; so it's probably going to be a magic overhaul. SM was the only one I saw on your list, but I only skimmed it... but now you know pretty much everything I do about the situation!