Not quite as complicated, but one of my favourites is the system Bulgaria used for the 2009 election. It was mostly typical PR in constituencies corresponding to counties (Sofia was split in three), but for some indecipherable reason, they also decided that each MMC should double as a single-member constituency. So 31 out of 240 seats were elected from these constituencies with wildly varying populations for no apparent reason. It was repealed before the next election.Ah, Eastern Europe and its mildly cursed electoral systems. I mean, single-member (with majority requirement but only in the first round), proportional, and nationwide leveling seats?
I don't have the census itself, but you can find just about any number you could dream of on this site: https://treemagic.org/rademacher/www.verwaltungsgeschichte.de/laender.htmlDo you have the 1925 census numbers at hand by any chance? I'm trying to get an idea of Bavaria's population evolution without the German refugees after WWII so it'd be super helpful.