well, if you can see it ingame, then there should be a script file for it somewhere. (yes its a npc) If there was no script, it wouldn't load and you'd get an error when loading m2server, and yes it will still load even if the script is incomplete or blank.
I get no yellow dot on the map, and moving the cursor over where it should be it doesnt come up with "chaos node" so i guess it aint there.
EDIT: I have just found ChaosNode-66.txt with the script for getting into lightning cave. There is nothing in TBL_NPC for chaos node so i guess i will have to add it then all will be ok..will report back to let everyone know.