So the Duchy of Alexandria is born.

Did Ferdinand changed how he looks at Rozemyne along the way? Something must have happened behind the scenes.

There was a motif somewhere about an arranged marriage leading to romantic love. Was that some sort of checkovs gun?

Rozemyne basically admits here that she is an aromantic.

Apart from the thing with the Great Library at an ocean coast, this new duchy shares some more things with the Earthen Alexandria. That too was founded by someone who was originally an invader, but became a well respected and liked local leader, albeit Alexander the Great became Pharao of the entire country of Egypt, rather than the archduke of “only” a single duchy. But hey, at least this Alexandria will unique with it’s name, while Alexander founded many Alexandrias in his conquered lands. ^^

The first thing I thought about for the crest animal was an Owl. I would have at least inquired with Ferdinand about whether their world too associated owls with wisdom and if so, picked that as the crest animal. With Dunkelfelger having the only bird among the crest animals - a hawk - it would still be very distinct from all other duchy animals and an association with Dunkelfelger would even be fitting, considering their role in the invasion.

I guess the library shumil are fitting, for those who make the correct mental association, but could easily be misinterpreted as depicting the feybasts, rather than the magic tools. Not to mention that the vast majority of nobles only known Schwartz and Weiss as just library assistants, and has no idea of how deadly they can be, and have never even heard of the scythe wielding killer bunnies in Ehrenfest.