There's a lot of really interesting lore hooks here, but the main thing I want to point out is that 'Thundran' is a top-tier lightning-elemental boss from a 90s video game. Like, I have absolutely fought that guy in Grandia.
More seriously:
So this gives us a LOT of broad timeline info on Preservation that we didn't have until now: namely, that they'd put Sphene in stasis before they knew any of what they were doing with her, and the Endless plan came later, with this story being in a period when they'd completely given up on a cure, but still hadn't figured out Endless yet. And yeah, even in this early state, they were going in on extortion and outright treason.
Also: Treno confirmed! Another FFIX city, Treno was probably one of the inspirations for Eulmore, is where you unlock the Tetra Master card game, and if I recall is the first time Kuja turns up. It's also one of the two IX towns used as lands in the FF MtG set, which of course, is only enjoyable to me. In terms of FFXIV lore, it shows that other cities were in lightning domes, so it's theoretically entirely possible that another city is just... out there on the Ninth, still stuck in that dome and with no idea what's happened.
EDIT: Also, thought I'd come back to add: this is one of my favorite of the Lodestone short stories to read, hat Preservation stuff is just dripping with a really menacing energy. This is the stuff I was hoping would be the sort of stuff I was hoping Calyx would be the head of, it's great!