Just someone who loves to read and doesn't mind where a story's from as long as it's good.
Hit up the Library Of Congress, then the Vatican's archives. Heck with the ability to reveal all flaws in a written work you could solve a lot of mysteries, like did Marilyn Monroe really die of accidental OD or was she murdered? A book on her life would end up with any flaws printed out including if it was false that she accidentally OD'd. Or was Oswald really a lone gunman or was he working for someone else like the Mob. You'd likely need some real serious bodyguards though once people realized you could do that though, all those powerful people wanting to get away with murder would NOT like you running loose to expose them.
Most aggravating thing is people like her exist in the real world (I've dealt with some myself, coming out on the losing end every time). Unlike in the story they almost never get their comeuppance in real life.
You have to wonder how many other guys came in innocently looking for something that she's subjected to this abusive behavior, because she's clearly living in a fantasy world where everything revolves around her and any young guy who comes in asking about things must be really after her instead. I've dealt with one of those trashy women myself at a place I worked at once, convinced herself because I was requesting the equipment I needed for repair work I was doing too much and that I was after her and even complained to the management about it. Wasn't even allowed to defend myself and got a black mark on my record for doing nothing thanks to a narcissist like this one.
Definitely one of my absolute favorite light novels (with A Will Eternal being the other). Just the idea he's a librarian from Earth entering a world where being a teacher is the most revered position in the world is a refreshing change of pace, it makes me wonder if the author is a teacher as it clearly throughout the novel presents them in such an awesome light. His successes and failed efforts to be humble and getting to watch various arrogant people get their faces slapped one after the other often without the MC even trying is just a delight. Really, the novel is just too wonderful to praise in just a few paragraphs.
That's not becoming a Karen he's got a legitimate reason to speak to her superior given her bad behavior. He's done nothing wrong and she's been clearly antagonistic and trouble-making, if anything SHE is the Karen.