>If that is the reason for the change, then you should adapt your app to get along with the data as mapped in OSM, not the other way around.

Sure, this approach is more than routine to us by now. That being said, if we detect some clear inconsistency in the results, then it feels appropriate to do the correction in OSM directly so others also profit from it. Indeed, some months ago we detected vandalism in UK counties that had managed to stay under the radar, and helped correct it. 

To add to the latest comment, this is what I already pointed out in my first reply: If the counties still have practical use, then a "historical" tag sounds inadequate. Seeing this tagging next to the information on Wikipedia, I (erroneously) assumed the counties were evidently no longer in use, hence the edit. 

It was never my intention to step on other people's toes. If the changes are incorrect, then by all means please feel free to rollback them. In retrospect, certainly we could have started this conversation on better footing. Still, I hope this has sparked some constructive discussion and I'm glad to see the boundaries are taken seriously by the community. (In my experience, not every OSM community cares as much about them, sadly.)