Well, we did hear Obi-Wan’s voice in TFA, so I assume his ghost is still around in some amount.
The forceback is still rather difficult to fit into this, as I don’t even think the times where the characters get visions of the future really compares well with it. For all we know it could even be a piecemeal construction from the thoughts of a sentient lightsabre (though where it got the information regarding the razing of Luke’s academy is a good question.)
Maybe it’s actually the crystal that powers the lightsaber. Not so much alive but a resonant frequency that only someone force capable could be affected by or connected to. Yoda said, “The force surrounds us, binds us, luminous beings are we”.
Just a thought anyways.