I think the OP was thinking of Dancer rather than Archer. The Totentantz is one of the few at-first-disconnected things that were picked up by Endwalker that I genuinely think they did include with the intention of it being a setup for the payoff; they would've had the nature of dynamis and the End of Days plotted out by then, so the fact it looks awfully similar is likely intentional. Especially given it's something observed by Thavnairians, who we know actually did theorize and discover this stuff.

But for the most part, yeah, Enkidoh kinda has it. Most of the threads tied together in Endwalker weren't introduced with the intention of ending where they did; it's been mentioned in a few interviews that a lot of those callbacks are, for the writers, more an exercise in figuring out which of the leftover plot hooks they have lying around would fit well for these. Some of those were orphaned hooks intended for a storyline that just never happened (famously, pretty much everything about the Ascians before approximately the Antitower), other things were outright introduced with the intention of just being an errant weird thing to maybe explore later (like, to the best of my knowledge, Kuribu).

That shouldn't be considered a discredit to the writers, it just means they're very good at an entirely different skill than it first looks like they are. It's genuine talent that we should recognize that they're able to go 'we need to justify this plot development we're doing now, let's drag in a storyline from nine years ago to make it look legit'.