As a native Chinese speaker, I'm terribly sorry to say this but the Mandarin that Jem speaks is literal shit from a butt. It gives me whiplash every single time because the way he speaks to Tessa in English is so lyrical and heartfelt and romantic while his Mandarin just sounds like he learned to speak it from Google Translate, except Google Translate probably didn't exist back in the Victorian era. It was so painful (not in a good way) and awkward to read that I was literally begging for him to cease professing his love for Tessa in Mandarin; absolutely no one who is a fluent speaker of Mandarin speaks the way he does. How on earth did whoever was in charge of his Mandarin lines make such a swoon-worthy man's declarations of love sound as stiff and soulless as Mortmain's automatons???