Two things I find frustrating:

1. FL entered this timeline suspecting a conspiracy of some sort, and found out there was a supernatural evil at work. Yet she seems to have absolutely no care about keeping an eye out for the forces at work against her. Hey, remember how you met that weird foreign nobleman, and immediately clocked that the lady he was with was acting out of character? And then you discovered he lied to you about his kingdom? No, not suspicious at all? Too bad, because if you were at all wary and kept an eye out for suspicious individuals plotting against you and your family, you might have noticed more noble ladies are acting weirdly around him and he infiltrated your household.
2. You've entirely accidentally discovered you have some kind of power to fight back the supernatural evil at work, and suddenly the Queen (and less suddenly, the King) are suffering from a mysterious non-infectious illness? I don't for sure that its part of the evil but, like, maybe just try praying at them, just to see if something happens.