Actaea

Regarding the old Arconia, I believe it should also be transcendental. That is, it exists, but it cannot influence anything. There is no trade with it, it does not help with its army, and it does not appoint a monarch to the throne.

That's exactly how it is. The connection between them is mythical, i.e., it exists, trade takes place, the population travels back and forth, but it does not affect the numbers. And also, the emperor's child arrives from there if needed.
Although I doubt that it will even be possible to create a war-torn continent.