I though my region list box handles Duchies pretty well, though yes it has issues with realms named after the capital. I haven't really looked at how to handle imperial regions though. The bigger problem for me about rolling the thing out is that semantic data still isn't updated without a page save. One way around it that might not be as big a resource drain as the standard semantic update script, would be to produce a couple of pages that import all the external data about regions etc, and then have a script update these pages at whatever interval.
If you look at the Arcaean region pages, you can see Part of is already holding multiple entries, so I'm not 100% on what the advantage of moving to record type property, unless this type would make it easier to figure out which on the entries is associated with a level of realm hierarchy?
