Specifically, I'm trying to figure out what the actual distances involved are. Could you see New Celest across the seas while standing at the edge of Magnagora? Or make out the Serenwilde from the mountains of Gaudiguch, assuming no obstacles in the way?
Certainly, we notice the effects of the various protective shields, but would this just be an event in the distant skies over the horizon, or can we actually discern the shields themselves?
Or, are the distances large enough that we couldn't even make out the Razines on the western horizon, while standing in Avechna's Teeth?
Mayor Steingrim, the Grand Schema says to you, "Well, as I recall you kinda leave a mark whereever you go."
Answers
I've always considered the Basin to be little more than the size of a central west-european nation, with the sea area in the middle more the size of say the channel gap than a full blown Atlantic divide.
I think elevation has a large significance in the matter, I'd expect, with the exceptions of being in heavily forested areas such as Glom and Seren, that you can make out Hallifax in the sky from anywhere, assuming there isn't a large raise or obstruction in the landmass between SoD and IS you can see Magnagora and Celest from each other's respective city walls.
And obviously being in Hallifax, you can see just about anywhere on the city's upper elevations.
The divine voice of Avechna, the Avenger reverberates powerfully, "Congratulations, Morkarion, you are the Bringer of Death indeed."
You see Estarra the Eternal shout, "Morkarion is no more! Mourn the mortal! But welcome True Ascendant Karlach, of the Realm of Death!
Estarra the Eternal says, "Give Shevat the floor please."
Or Daraius may be right, maybe Lusternia is more like mythical worlds of old, which were flat.
Estarra the Eternal says, "Give Shevat the floor please."
Then look at this quote from the Book of Dracnoris: "After the disappearance of the three children of Yudhe, when the Great Silence fell across creation, when the Elder Gods, myself included, were drawn to the First World called Lusternia" Looking at that quote and taking knowledge from Lusty's histories, I would say the First World is just a leftover creation creche that Dynara used to create life, that still carries the echo of Yudhe, which allows Elder gods to create life like Dynara.