Well, the addition of the sound.json file makes the playsound command run sounds from those patterns not from the file path. The sound for random.fuse is accessed via game.tnt.primed
What on earth! One moment it was like that I swear, and now it's no longer.... Well, Bug Busted.
Well I don't think mojang ever meant it to be like this. This is a cool thing to have but I think "killed by magic" is there for a specific reason.
It's not doing it for me. Are you sure you had particles on?