I don't see any changes comments yet that elaborate on this change. Have you spoken at all with the local community about this beforehand? (This borough/town designation seems to be a recurring issue from what I've heard.)

It's also best not to publish a large-scale change like this merely for making a label render better on OSM Carto. 

Try to consider the following.
https://wiki.openstreetmap.org/wiki/Tagging_for_the_renderer