Lintons is one of my favourite ever CS books, partly because I think it was the first one I ever read, when I was about nine, and rather confused by mentions of the Sonnalpe and curtsying and Kaffee und Kuchen etc. I'm not even sure I knew what TB was.
I love it now as an adult because of the set pieces (Mrs Jarley, the Home Economics class, the naming party at the Sonnalpe, the midnight feast), and the completely mad stuff, like Joey not noticing Madge is heavily pregnant and Madge hinting but not saying anything.
And the stuff that has aged spectacularly badly, like Joyce Linton and co pretending to be 'savages' in poor Miss Norman's class, and essentially playing blackface, with talk of corroborees, Joyce making her hair 'fuzzy', people putting feathers in their hair and painting tattoos on themselves and talking in 'grunts and clicks'.
I think both Thekla and Joyce get into undue trouble if you compare it to stuff people get away with scot-free in later books eg Margot braining someone with a bookend or Jack Lambert bullying Jane quite badly.
Thekla doesn't even show up to the class where the rest torment Miss Norman, she attends a midnight feast, is generally an unpleasant snob (but she's hardly unique in the history of the CS in that) and her crowning misdeed is getting Joyce out of bed at night and being unrepentant about it. OK, it's supposed to be part of getting Joyce into trouble to annoy Joey, but that campaign never actually gets under way.
It seems a bit bad to expel her when someone who causes a potentially serious head injury to another girl after losing her temper doesn't get anywhere near expulsion!