I am also curious about going to war with other countries and if it gets implemented; do the guards automatically attack you if you enter a town or settlement that is a part of the neighboring country that you're in war against? if let's says that is the case: do NPCs permanently die if you kill them?.. or is it just via the battle system on the overview map?... sorry for the weird questions.. just curious and all.
It's planned in such a way that you only do the preperations pre-time skip, and then during the time skip events you'll fight the war against the other countries on a map similar to the overview map, with the option to use the vanguards and their battle system to get advantages in the war. You won't be able to run into enemy territory with your party during a war.
I think war system could be exclusive to an evil route of sorts. If you go to war with countries you're actively helping it wouldn't make sense. Like, once Varea gets the throne you and Amagal will be allies for life, you shouldn't be able to go to war with them, it would be weird to slap a war system in this already established foundation you got going.