Eorzea or Etheirys?

[Iscah]

In the strictest of senses, the "real world" seems more like Aldenard is Africa...

Aldenard is not Africa. It is, loosely, Europe turned sideways (before they started aiming for a 1:1 comparison to an Earth map at a large scale), maybe with the northern bit of Africa fused into it, but not the whole continent.

Everything we know so far to be "Meracydian" is from Africa. Maybe it's a hybrid Africa-Australia but we've seen no indication of it to this point. It's more like Africa detached from Europe and drifted southeast.

Meanwhile, Ilsabard seems to be Russia detached from the rest of Asia, which has slid off horizontally to the east to become Othard – which is presumably why they seem to be having a hard time actually squeezing it all into the globe at a convincing size and leaving so much of it as blank ocean.