You have to pick the first option in the book reading event to get him to talk about the book he was reading. If you haven't gotten it yet and he quizzes you early, just keep going through the loops and take note of things he says he likes or things he does/observes, you'll get the interaction eventually. Mine was Pride and Prejudice for example.
All of my questions and answers were in Chinese, so I used my phone with Google Translate and everything matched the translation. I think the only set of answers that might be difficult to understand is what's L's wish. Good luck!