I still don't see an explanation for the kerosene smell. I assume nobody
knows?

I've often smelled jet-engine exhaust (mainly the smell of jet fuel) after
landing. I assume this is exhaust partially drawn back into the engine and
the packs, but I don't really know. As for the smell in flight, that would be
unusual, and it's not obvious how exhaust could find its way back into the
packs.