Honestly, the bones of a good game are there, but like others have mentioned (on a quick read through to make sure I'm not parroting anything already mentioned and trying to add something new to the discussion), it's odd that in a Matriarchal Monarchy, the heir who chose to give up his masculinity is being degraded and led down a submissive path when instead the loyal court members should be doing everything in their power to help and empower the Prince-turned-Princess to become the heir that their kingdom needs. Especially considering the latest update's world building.
If there was a plot thread of traitor trying to weaken the line in any way in their midst and the MC's unique position gives them some insight into finding who it is, maybe that inconsistency might be explained, especially if the player has to gather the right evidence to lay their claim before the queen and the rest of the council. Likewise maybe some lessons were actually traps put there by the advisors with permission of the Queen to test how the MC deals with subversions of the Throne's authority on their own with the Queen giving hints every so often, failure meaning the whole stops, he regains his masculinity and married off to a cousin who becomes the new Queen. Otherwise, from what I've read into the setting before the sissification, submission, and humiliation turned me away, the Prince/Princess really should be playing catch up with his/her new duties, responsibilities, and bearing as a Princess.
Though one thing I'm wondering, ultimately speaking, would the player be able to choose their future partner depending on which genitals they end up keeping? Like say instead of a King Consort, could the MC have an option of a Queen Consort from a neighbouring Kingdom instead? Actually, that might be something to look into and write about, the neighboring kingdoms or local nobles that might either help or hinder the MC's kingdom, likewise their reactions to the MC's choice. There's quite a bit you can play with here Dev, I really hope you take advantage of it because you've got something that can end up being gold.