Issac and his three wives left Brandenburg seven days after completing their mission. During those seven days, Issac toured several areas outside of Brandenburg.
The development here is indeed uneven because it is focused on Brandenburg. That's a reasonable decision. In the early days of Aurellia in power, Aurellia also did the same thing.
But what happened in this kingdom was something exploitative. Many of its citizens are forced to become coolie labourers without being paid. They are also not well fed. Construction in Brandenburg was going relatively fast, but discontent among the people was bound to increase.
It was seen when Issac strolled with Agatha in a rather large town, a few kilometres from Brandenburg. A group of soldiers led lush youths with thin and dishevelled bodies towards Brandenburg.
In addition, there are fairly large wagons pulled by three horses carrying various items such as logs, lumps of stone, and women who were enslaved.