But why would Kanan sense her presence if she was dead? I've never heard of a Jedi sensing a corpse before without realizing it.
Yeah I was wondering that too. But maybe before she died they found some way to extract or contain her force energy before it could move on, so it could be used as a lure for other Jedi.
Or maybe their energy doesn't actually leave the body and move on until they've been cremated in one of those giant bonfires they like so much.
"Luminous beings are we, not this crude matter."
But that crude matter contained energy for awhile and may still leave a lingering trace of a person in the Force after they're deceased for awhile, IMO. Luminara's remains seemed to be fairly well-preserved though, perhaps keeping that trace of her preserved as well.
Total Jedi bait.