My goof! I meant Elidibus, I know Lahabrea's been out of the picture for a while.
IDK, Urianger and the Exarch's scenes about in ShB make it seem like the effects spread past Eorzea and Garlemald and into the Far East too. We could also interpret those scenes to mean that civilization across the globe collapsed from both the Black Rose's effects and the whole "Mad Max" fall of civilization, but they keep using the word
world, not just Eorzea.
Grand-Biggs' last message to the Exarch at the end of the Twinning also has him saying
he doesn't expect the world to last much longer. YMMV how literal he's being about that - to me, it doesn't make sense that EVERYTHING would go to hell as badly as it has in the Eighth Calamity if the damage to the planet (where apparently, they can't even grow crops anymore!) was just limited to where BR was deployed.
It's something that has me (morbidly) curious, and I really hope we find out more about the Bad Future in the patches. It's amazing to me that after all Ironworks accomplished, Cid still found it more practical to
invent time travel than heal the damage from Black Rose.