Geographically, I would say that Shposhae is that cave to the north-east right as you exit Limsa into Lower La Noscea (the cave with the Raw Ruby unspoiled mining point). There's that stream with all the frogs that leads to a cave that just kinda stops part-way in. I assume it caved in when the Calamity hit. That would line it up pretty well to where it was in 1.0.
Sastasha is almost certainly their attempt at fleshing out one of the more elaborate caves to the North-West of Limsa back in 1.0. In there, there were pirates and slimes and ended at some underground docks. Edit: In 1.0 it was called Mistbeard Cove.
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