I'm disappointed in myself that I couldn't at least get Rowling right! I read the series only a couple years ago, and was completely stumped on that third sample still lol. I thought I'd be a little better at identifying her "idiolect." But then, revisiting her books one of the things that surprised me most, especially early on, was how unspectacular her writing is. It was around Goblet of fire I remember feeling that she'd finally begun to cultivate more of an interesting and unique voice for herself. I didn't recognize that sample at all though!