I suppose at the time of Sweden's unification it was more about subjugating ones political enemies on horseback rather than attempting to harmonize the existing processes of a huge number of modern polities. Yield! Kneel! Pay your taxes! - and then off to the next battle.

They spoke the same language, it was basically happening in the context of feudal system which was from the point of view of the operations of government modular - basically the whole political system supported pretty well constant shifting of the ruling body - I kneel to you, they kneel to me, and I give you some grain and provide men in time of war. And ruling was pretty simple back then.

Before 1600:s the function of government was basically the king. After they figured out there must be a better way to rule than riding ones bottom sore ruling and taxing about modern state functions began to emerge. I believe this was at the time of Gustavus Adolphus II in sweden (https://en.wikipedia.org/wiki/Gustavus_Adolphus_of_Sweden).