One thing that you have to be good at doing, writing a serialized piece of fiction across a decade, written by who knows how many other hands, going through permutations, is learning how to look at what went before and find hooks and themes. To look at previous works and go "hey, what if we did THIS?"
Which brings me to the discourse around the usage of Answers in Endwalker.
Using that song for Venat's walk in particular and in many places with Hydaelyn in Endwalker was, of course, a slam dunk, obvious choice. It's basically the themes of FFXIV in general and Endwalker in particular, closely associated with Hydaelyn, and all that jazz. And it is used to devastating effect. In fact, failing to use Answers in Endwalker would have been a colossal failure; it simply had to be used. It's too closely associated with Hydaelyn and therefore has to be associated with Venat. You could interpret the story to say "you, the Warrior of Light, are her answer." You had to write around it.
However...there were people, upon finishing 6.0, who rushed to the internet to say "oh my god they had the whole story planned since 1.0 when they wrote Answers!"
And no, of course they didn't. That was a completely different staff, with a completely different story and a completely different endpoint-assuming they even HAD one. They had no idea, when they made 1.0, that one day a character named after another character from FFXII was going to be walking through the ruins of a civilization destroyed by a bird girl manifestation of the Fermi Paradox, and the game's major theme song was telling that story a decade in advance. Someone looked back and said "okay we HAVE to use this."
The story of FFXIV has always been in flux, and always will be by nature of its creation. Look at the way they had to keep explaining why Lahabrea was such a pushover in ARR while Emet-Selch and Elidibus were borderline gods, until they finally gave up and reworked the Lahabread fight in ARR to match the scale of the later Unsundered fights. The Mothercrystal going from "the actual heart of the planet and Hydaelyn Herself" to "actually, a stockpile of aether, Hydaelyn's over there and she's got WINGS" should prove that.
(For my part, I think that all of Hydaelyn's cutscenes and appearances in ARR were just Venat hiding behind the Mother Crystal, throwing her voice and trying not to giggle at her spark. She's that kind of gremlin.)
And yeah, you also have to consider the localization issue. One of the more infamous story differences that I have heard of, and that's also a bit of a game of telephone in how the story is perceived, is that the notion that Y'shtola using aethersight is killing her only exists in the ENG localization. Midgarsormr's motives for removing the blessing of Hydaeyn is utterly different. Hien's "well sure he's a human trafficker but he gave me a hand!" moment is not present anywhere else. Four different localizations adding more cooks to the kitchen.
Things get dropped all the time. Zenos dreaming of the Final Days in Amaurot sure seemed to be a lot more significant than it ended up being. Black Rose disappearing in a single cutscene, basically rendering ALL of the Shadowbringers MSQ irrelevant since Zenos would have likely always stopped the use of Black Rose to allow him to have his magnificent battle. The Ivalice story, which had spread from Stormblood to Shadowbringers, across three Alliance raids, the SHB relic quests and two different zones, was wrapped up off camera in a single character bio, and has seemingly been abandoned. There is no One Intended Truth in game where plots can be canned like Ivalice was, or the next lead writer can decide to go another way (seriously, look at the plot strands leading up to and after Ishikawa became the lead writer.) and where canon is often determined by who has the microphone at a particular event. Just enjoy the ride.
