At this point, it'd surely be less taxing on the database server than having to scroll around, zooming in and out, querying thousands of segments with the highlighting script -- and even then not finding it.
And after all that work, six months later the city area layer haven't yet been updated and people still complain about a damn city name on the wrong segment on the wrong place that makes that small city become more prominent than, and even over, Lisbon, the capital of Portugal
we all hate that city these days, it's everywhere we drive.
At a certain point I just gave up and drawn "other" landmarks over the cities, first to use the extensions scripts to do a mass city set, but just kept them around.
Maybe it's better to forget the automatically city-areas and just let the editors draw them out, with a special landmark with a different colour than most other landmarks - the only disadvantage right now, every landmark not park/green or gas mostly blends with the city area