Nope. His father was never high on the royal hierarchy and only became Zent because everyone else got killed. After that, the family was barely keeping the country from falling apart after the civil war. It's perfectly normal that an expensive personal library wouldn't be high on his agenda. And since everyone is trying to keep Rozemyne's personality under wraps, especially towards the royals, it's understandable that they don't know what the right bait would be to hook her.