Thanks for all the details. It is strange that your stats didn’t change at all after the session. It would suggest that something isn’t syncing properly on your account. The fact that the item isn’t coming back early in the next session is also suggestive of this.
I would recommend upgrading to the latest iOS beta 3.4.1 (300386), which was just released on Test Flight, and doing a fresh log in on your account. Btw, we’ve affectionately been calling it the Apmixis patch internally because of all your great 3.4.0 feedback 
If you’re still seeing the Pinyin/Definition grading issue after a fresh install post below so we can investigate!
We’ll look at the word-level grading and see what’s up. Could be a flaw in the logic when going back to change grades, or maybe just a typo in the code. We’ll dig in!