Is this mod compatible with K2 or SE?

Wrt K2: Yes, as far as I know.

Have current game with K2 and haven't seen any issues myself.
I think someone reported here an issue with Tesla Coils in K2, but I've yet to build these in my game, and didn't check via /cheat, so not sure if it might just be something else in their game instead.

Don't know what SE is (and lazy to google), but I assume some other big mod, and don't think there should be any issues there either.

In general (and in my experience), factorio mods are very well-insulated from others (unless you deliberately break that), and only conflict in their obvious effects on the game - e.g. a mod that removes all enemies and mod that adds enemies will be "in conflict" in that you might not get exact effect of one of them.
Another common conflict might be mods that add technologies and mods that remove them - this one adds UV Lamps to Optics tech (iirc), and Wisp Detectors with its own tree node, but these are completely optional (purple wisp damage should be default-disabled in current version), and pretty sure usually big mods (incl. K2) don't remove vanilla research tree nodes.
(exception is Industrial Revolution mod, which had entirely different tech tree and techs in general, divided into "ages", but dunno of any other mod that does the same)

Also check mod options, as they allow to change this mod's behavior quite a bit, to tailor what it does to e.g. how other big mods in your game work.

So, to summarize - compatible and kinda-tested with K2, dunno what SE is, and probably safe to assume that it's compatible with everything by default, unless there's a bug (usually easy to fix, just report it).

Okay, tested it extensively. Works fine with K2 alone, but works fine with SE and K2SE ground surfaces till you get up to space.

SE = Space Exploration btw

On space surfaces in SE, there's no trees so no yellow wisps but mining a rock on an asteroid in Nauvis orbit spawned a red wisp. I also noticed an invisible purple wisp spawning on the star map surface. Also planets with 0% threat should also not spawn wisps imo

I've got a saved game that has SE + K2 + Will-o'-the-Wisps (among many others) for debugging one of my mods. On loading it, the following warning is printed to the console:

There is 1 item that exceeds the recommended stack size.
Cross-surface logistics are designed for stack sizes around 10-200. The cost of transporting materials between surfaces is a core part of Space Exploration gameplay.

List of oversized item stacks:
Alien flora sample: 500 (Recommended: 200)

Even if it's just a harmless warning, I'd suggest to adjust the stacksize if SE active. After all, getting rid of this warning should be trivial. :-D

Yeah, should fixed to be 200 in 0.3.28. Thanks for reporting.
Suspect 500 might've been a misspelling of 50 in the old original mod.
Not entirely sure what it'll do to possible existing stacks of this intermediate item, but don't think these should ever be kept around anyway.

Yeah, should fixed to be 200 in 0.3.28. Thanks for reporting.

Thanks for fixing this!

Not entirely sure what it'll do to possible existing stacks of this intermediate item …

You can ignore them. This explains what will happen.