They have literally said it is symbolic, and we have a Lodestone story released after Endwalker featuring Venat and the Watcher at the time shortly before the Sundering—which is still canon to Endwalker. It wasn't retconned, it was a cinematic representation of Venat's guilt and burden presented through cutscene form. It's a scene meant to make us feel bad for her and that's all it is.
Ask yourself questions about what is shown, if it makes sense (90% of it doesn't):
Did Emet-Selch stand in the midst of Amaurot while the Final Days was happening and Hythlodaeus ran off to become part of Zodiark? Absolutely not. Emet-Selch was probably stuck with the Convocation preparing for Zodiark's summoning, as it was their doing. He and Hermes, now Fandaniel, were also shown without their masks—a major taboo in Amaurot, espescially for those of the Convocation.
Was a group of random yay-hoos unassociated to the Convocation the people who sacrificed others to Zodiark? Like the scene implied? No. The convocation made those decisions, the populace was like sheep to the slaughter underneath their control and guidance, they had no choice in the matter.
Further, its established even in 6.X that Venat had followers, many followers. Those followers and she of who chose to sacrifice half the remaining population to create Hydaelyn (revealed in 5.2). It wasn't a decision she herself made and the revelation in Myths of a Realm and through the Lodestone story with the Watcher confirm that this is still the case.
There are so many inconsistencies and nonsense depictions in that scene that its actually hilarious when you look at what's going on. Honestly, how anyone can take it seriously and think it is a continuity error genuinely confuses me.
None of what happened in that scene made sense, the Final Days was stopped before the sundering happened, the scene shows it going on concurrently even though what we're supposedly witnessing there is the second set of sacrifices which was what brought life back to the planet.
That right there was the dead giveaway that the scene was worthless, cinematic drivel that was meant to make us feel bad for Venat/Hydaelyn and nothing more.
Its a bad, poorly written scene that served no narrative purpose other than to try and make us feel bad for Hydaelyn and that's all it was.
You need to understand that our visit to Elpis changed nothing, it had already happened by the time we had gone there, which is why its a loop.
Everything happened the way we already knew it had because everything was already pre-ordained to take place.
For Endwalker's narrative to even work, nothing could change, that was the whole point. Meaning we always had gone to Elpis, we were always Hydaelyn's inspiration, she always knew about the future, and she always chose to remain silent despite the information she knew.
I figure the reasoning was: "Well the players already know all this pre-established information, so there's no need to have that represented in the scene as they won't question it," which is, often a direction they do go with the narrative. Why suddenly people think its different here is beyond me. lol
Its paradoxical and frankly silly, but its the direction they went with.