When Zeng Jinghan accepted an offer to lead the Confucius Institute at Lancaster University in England in 2018, he already had a plan to write a book. “I thought it would be very interesting if I could write about something that I know a lot about and participate in it personally, like Richard Crossman’s The Diary of a Cabinet Minister,” Zeng said, referring to the British politician’s memoirs published half a century ago. The job did not offer higher pay, and he was still an international...