Let's look at a similar situation.
Harry walks in and uses his little candle lighting spell to light a bunch of candles.
Then, one gets knocked over.
The place burns down and kill some mortals.
Harry is TECHNICALLY guilty of murder, but there would be no council, or cosmic consequences.
I think it's more about the letter of the law and the way the magic is applied. If I cast fire on your face I have to believe in it and my right to do so for it to work, and thus I have killed with magic and broken the first rule.
If I cast fire on a candle and then use said candle to burn your bed I have broken no law of magic. I simply lit a candle. The rest was physics.
Moral I'm still guilty. Same as stabing someone through the neck with a sword. But by the law I'm clear