While Rozemyne is an official translation, I find it amusing, that German word for a rose (I guess it was supposed to be the flower in the name) is "die Rose". But the "z" sound you expect is still there. Generally, german "s" sounds like "z" in pairs of s+vowel.
They didn't include the part where she explains Deliah fears the orphanage and hates it, this it would be a fitting punishment.
It is Sylvester we are talking about, he never was the smartest person. From his perspective:
He felt he should never have been the archduke and that Fernand should have been. Therefore a lot of times he just follows Fernand's plan. And Fernand hates his mother and would obviously include her downfall in his plan.
He likely naively felt the prosecuted faction would accept him after his sacrifice and that the old faction have no choice but to follow him.
The mother also was harsh on both Fernand and his wife. She also treated Sylvester a lot like a puppet. So he also had emotional reasons to distance her
Also, his mother's faction doesn't hold the dutchy together. His mother's faction is the minority. From his personal family perspective it was a bad move, but from the dutchy perspective it was a good move. Because the minority prosecuting the majority is a ticking bomb.
Sylvester has always attempted to remove his mother from power for various reasons. His mothers faction is his powerbase but due to her influence she has more authority over them than he does and it has caused major issues for the people he cares about. He couldnt overtly move against her due to how powerful her faction was and if he tried removing her via the usual ways he would find himself dealing with a civil war and outed. He first tried via reducing her influence and found himself stopped at every turn by his retainers and her people. He couldnt just eliminate her either because of his feeling towards her and what her faction would do after she died.
This plan was all him. All of his retainers, the opposing faction, and even Ferdinand didnt know about it. Hell Ferdinand only learned about his intent to adopt myne when he saw the black charm. Sylvester gave the charm to myne not only to protect her and give him justification to directly intervene for her but also as a deliberate trap for his mother. He may not have known precisely how she would have gotten involved but due to the high bishops constant abuses he figured she would get involved and then could he reduce/remove her influence. Luckily for him she left evidence of her committing a unforgivable crime that he can use to formally arrest her and her faction doesnt have much justification to rebel since it is one of those crimes that is well within his rights to punish accordingly.
It's not directly stated, but I believe it is a 40k reference.
Exchange about color in the novel:
“Why is ‘Red Myne’ one of your suggestions? Your color would be blue based on your birth, midnight blue based on your hair, or gold based on your eyes. Where are you getting red from?”
“I don’t really understand this myself, but red versions of people tend to be, like, stronger, or faster.”
Sylvester gave me a weird look, but I was basing that off of something my childhood friend from my Urano days had told me, so I didn’t really have a strong grasp on the concept myself.