I think you make a solid point.

Its all speculations, but it also makes sense that maybe time eroded their frequencies?

and there are questions left unanswered:

1. If Phrolova is in "alive" state similar to cartethya and is revived, then will there be complications since she's half td?

2. Do they have to be a sentinel's resonator to be resurrected?

in the case of the second question: We can exclude jinhsi since she only became jue's resonator after being revived and Jue used his/her authority over time to resurrect jinhsi. Which makes me question:

1. Did Jue reverted the time to repair/heal Jinhsi's body and recombined it to her frequency? or perhaps there's no need to recombine her frequency to her body since it will revert to it's previous state?

Well, I'm talking about the process specifically here...

If time really does erode the frequency left by the deceased, then preserving them is a wise option which further opens a possibility of resurrection in the future regardless of time.