Regarding their next 'actual' rank I still think they would evaluate a bit lower than where Alexandria should be simply because Rozemyne's library strategy will take some time to take effect but once it does they could feasibly reach #1 and stay there. Alexandria as is simply is not focusing on anything that produces immediate tangible "duchy points" so to speak. Education and knowledge are abstract concepts that seemingly don't influence the rankings nearly as much as hard achievements do. Though the latter is just a consequence of the former.
Not that anyone will complain about the Divine Avatar not dominating the rankings, which will just be another behind the scenes factor. Rozemyne very clearly can't be bothered about her duchy's rank and I imagine Ferdinand would like to avoid the hassle that comes with it as well for a good while. Up until some fool mocks his wife or their adoptive daughter for it, then the gloves come off, in the latter case whoever did it better run because they're in for a divine crushing.
Not sure but imo whether or not it has been done doesn't really matter. If any one of the Dunkelfelger women up and just did it I don't think anyone would dare to question it, so it might as well be established fact.