If the border is in dispute, that is adversarial. The properties in question have openly and notoriously been subject to jurisdiction and taxation for centuries. Leave the border where it is, historical surveying error or not.
I have a stupid question.
Did anyone in the affected properties complain about this situation? Was the alleged uncertainty about the exact location of the border causing anyone difficulty with property ownership, business ownership, any other difficulty in their lives, by not knowing to the centimeter, where the exact border between the states is supposed to be????
The border was not in dispute. It was a mistake. Mistakes don’t count.