No specific advice for this carrier, but in general the name on the ticket does not need to exactly match the name on the passport (with the possible exception of Chinese Names and China, as you note.)

There needs to be enough correlation between the name on the ticket and the person travel document so that the check in agent doesn't suspect that someone else is trying to use the ticket. Typos, missing names, names in wrong order and other manglement are all business as usual because of the constraints imposed by Amadeus and Sabre and airline systems on name fields. So your middle name being missing is nothing to be concerned about in my opinion.

What does matter is that your API data does reflect the exact name on your passport, but this will be corrected for you at check in when they swipe your passport.

Enjoy your flight!