You're not telling me anything I don't already know. Like I said, those are the emotional beats of the story. They make sense. I'm talking about the metaphysical mechanics of Ryne and Minfilia's souls, and how the story fails to consistently define them.

An example: The Warrior of Light (the player) has the Echo because they inherited it from their distant past life as Azem. It's something intrinsic to their very being. This would also be true for Minfilia, as she too possessed the Echo. But there's more than enough evidence in Shadowbringers to suggest that Ryne does not. This would work if Ryne wasn't Minfilia's reincarnation, but a separate person possessed by her ala Lahabrea with Thancred.

But then there's the Quest On Thin Ice, wherein Ryne gets the bright idea to become the primal Shiva. To control a primal in such a fashion, one requires the Echo. The writers know this, because they're the ones who wrote it. The Scions know this, because of firsthand experience. Mikoto—an Archon unaffiliated with the Scions—know this, because it was detailed in the report the Scions made regarding Shiva after the initial encounter with her. Ryne doesn't know this, because she's a teenage girl from a different world who had never even seen a primal before, and whose knowledge of them is entirely from her mentors (you, Thancred, and Urianger).

Somehow, this important bit of information fails to crop up at all in this quest. It's as if the characters simply assumed Ryne had the Echo because "she's a reincarnation of Minfilia".

This isn't the first time this weirdness in their relationship crops up, and it's ignored every single time. Thancred ignores it when Minfilia tells him right to his face what the deal is. The WoL ignores it when relating Thancred and Ryne's story to Sidurgu, who sums it up as "Thancred had to take care of the reincarnation of his dead daughter". Alisaie, Alphinaud, and the WoL ignore it when their discussion of Warriors of Light prompts Ryne to offhandedly mention that she's never heard Hydaelyn speak—even though not too long ago, everyone who had the Echo (or just awakened to it) heard her. And yes, the WoL did hear that, despite some players' insistence to the contrary. And Ryne ignores it in her farewell to Thancred when she thanks him for making her who she is: Ryne and Minfilia.