There is one big thing about this theory that either makes it not work out or it leads into something else that would be really cool. What happened to Chanarach's Honor Blade? If she had died and was sent back to Braize like Taln was at the end of the previous desolation, then I believe her honor blade would have disappeared from Shinovar and gone with her. In a Taravangian interlude in Words of Radiance, Taravangian "lies" to Szeth about another missing honor blade among the seven remaining honor blades. This means before Szeth left Shinovar there were two honor blades that were missing as when he left he took Jezrien's honor blade with him. One of these of course would have been Taln's blade. We could assume that the other missing one is Nale's honor blade. This would indicate that Chanarach's blade was still there and hence she couldn't have died and went back to Braize (if this is the case then I am really sad because I loved this theory).
The OTHER possibility is that Nale hadn't yet retrieved his honor blade before Szeth left Shinovar as he could have still grabbed it well before the beginning of the Way of Kings (prologue time period) without Szeth's knowledge. In this case, Taravangian's lie about an Honor blade going missing is actually a hint that this is the case and the missing blade is Nale's while Chanarach's blade had already gone missing during Szeth's time in Shinovar which I believe lines up with when Shallan kills her mom. If this had happened though, then the ones guarding the honor blades (Szeth's family) may have faced punishment, tried to hide the fact the blade went missing, or perhaps have been part of the impetuous for Szeth making the claim that the Radiants and the Desolations had returned or would return. Brandon could be saving this big reveal to be in Szeth's flashbacks, while strategically not letting any of Szeth's current viewpoints mention Chanarach's missing blade and instead just focusing on Radiants returning. Anyways, this would be really cool, but I feel like Brandon would have foreshadowed this a bit more if it were the case.