Yeah, I am assuming that the memoirs will tend to be factually wrong (when they are wrong) at the points where she's describing other people's actions / things she only knows by hearsay, the more sensational the better (e.g., Grumpkow being part of an assassination plot!!) and reasonably accurate when Wilhelmine is describing her own experiences, though I'm allowing for some memory/bias there too.

But what kills me are all the times where she's all "and then the king grabbed me by the hair and dragged me through the room and it pretty much sucked" and "and then the queen told me, 'you've ruined my life and you're the worst daughter ever and I hate you and you should die in a fire', and it made me sad" totally matter-of-factly, like it's totally normal and of course you'd expect your parents to do that. That more than anything else tells me that it really was that bad.