I think it would look much better if we had both continents on one map, but only
MA knows if they are positioned exactly like on your map JC. Plus, having them on separate ones gives them the freedom of adding another continent if they need it without modifying existing map, changing the scale and so on. If they new exactly, how Calypso will look like in the future, they could go for one map. Or, if they marked some landscape as central, and expanded the world by adding another lands on the borders.
Still, it's kinda funny that Amethera has been discovered. I would expect that in the age of space travel, planet should be explored before first human even set foot on it
But, there are many things in this universe that doesn't fit SF theme at all...