The only failure i see in this arc was the excess of events in the final part, which is pretty forgettable after it ended, the author should be more proud of himself, he has amazing writing and artistic abilities more so when this is his first work.
Beibei returns, say what you say and i understand not liking her ( her first appearances weren't very good ) but she truly cares for Mo, the other guy too, they are good friends if they are willing to risk their lives in such dangerous places more so with their respective situations.