Why does Kaiser's teacher have to be batshit insane
Because there are many degenerates who are not only into that sort of thing, but will somehow imagine flimsy positive character traits alongside the the very real host of negative ones in such characters--perhaps to validate their lust for flagrantly horrible people. It is, now that I think of it, not unlike what girls do (or what I've seen them do) with vicious/villainous pretty boys. (See
Tokyo Ghoul as an example.)
The only thing worse than an obnoxious brat is a
powerful obnoxious brat. The story already has one in Regina (an extra whose disappearance the story would not be harmed by
at all), and is now poised to introduce another--and, of course, it's an all-powerful loli. Probably millions of years old.
Speaking of Regina: inflicts upon the kingdom definite millions of its currency in damage of various sorts, which was almost certainly accompanied by dozens of casualties--and she gets into the castle like a VIP. The extras are where this story's writing takes a steep dive, and I bet the new loli will be another instance of such.
That aside, Meryl doesn't seem to get that she can't be "daddy's little girl" and his wife at the same time. Kaiser, they should be able to see, is (written as) a blockhead when it comes to women (minus the feelings of the militant misandrist maid), and therefore will see his daughters as nothing but if they accept that even in the slightest; he will never see them as women if they don't grow up and dispel his illusion of them. At least the better and best girls (Anna and Elsa respectively) get this, at least implicitly: Anna is Anna, it's only natural for her given her character; Elsa wants to catch up to Kaiser in strength and be worthy of standing next to him--not standing behind and beneath him.