Feels like the endings should provide something (if not More Achievements)... Perhaps getting the perfect ending for a kingdom, or a particular action, could give a boost to that background?
E.g. Jiyel-Arland golden age would give boosts to the Scholar and the Princess... I was going to say additional boosts related to their respective kingdom (so Int for the Scholar and Etiquette for the Princess), but it would be really cute to get a boost for the other country's, since you managed to make them get along?? So it would get Int for the Princess?
Or perhaps simply boosts to Approval from the concerned countries?
Setting up the trade agreements or getting all the perfect gifts could get Merchants approval, etc.