Yes he caused it. Just as he will get exp if he starts a rockslide and buries a town, he will get chaos points if his actions lead directly to the death of another chaos seed. He will also get chaos points if his subordinates make the kill, but likely not if said subordinate is also a chaos seed? Could it be Heman got the points for his subordinates kill, because he had the strongest claim on the points amongst those eligible?
I put yes but brings up interesting point. If you are moving a force through kobold territory and one of your peoe gets killed by a random trap but the rest survive. Will the kobold that set the trap get the experience and know someone is moving into his territory? Would only work for specific location if each kobold takes one tunnel/ area or only uses a certain kind of trap in one area. Example prompt: you killed x with y trap for z xp.
In The Mayor of NoobTown series the MC set Traps for a bunch of Goblins in a fight he was having with them and weeks later he was suddenly informed by Prompt that he had Killed a Human Brigand/Bandit with a Trap, and due to the fact that those Goblin Killing Traps where the only ones he had made in that time he new where he could find some Bandits that he had been looking for. But if there had been multiple places with Traps he wouldn't have known where it had been set off. So I would think that in The Land unless the Prompts informs you of what type of Trap it was that Killed something then it's unlikely that you will know where a Trap has gone off at (unless you are only placing Traps in one place?), and I would suspect that Trap Prompts (for kills, ect) may not appear naturally and inform you of its use like those you get for Crafting and straight up Fighting but would have to be Manually Checked so to speak, especially if you are not near it when it goes off, although there maybe a Talent that allows for that.