I'll warn you that, if you are looking for a stable medieval setting, this story is the one that you should stay the furthest away from.
As a reader of the WN, up to chapter 636 (the latest one):
- The nobles don't have a family name. For example, what is Caroline's family name? Even her father is "Baron Frederick". And Josette's father is always called just as "Duke", and her brothers, sisters and mother just by their names, we never get their family names. Even the Royal family doesn't have family names, even the capture target's families are merely referred by their positions (Prime Minister and son of Prime Minister for example).
- The Kingdom also doesn't have a name, same for the nearby places like the enemy Principality. Seriously, there are about 4 named places: Tior (main city), Sanputo (Carol's father's new territory), Cogena (Supposedly Rachel's home village) and Raoci (Tia-sensei's home village).
The economy also doesn't make much sense, with so much money being spend in Kent's terminal that can't return to the economy that it's amazing that there has been no deflation, in fact, Duke's family must have infinite money.
So yeah, all settings are just for reader (Japanese) convenience.