Hi, thank you for playing this game! Chain's route is less straight forward. Players will likely post a guide later, so for now I'll give a hint:
Chain's 1st bad ending is by getting all choices without the ping sound (you'll stumble upon the secret ending too). The second bad ending is reach his romantic end ("Chapter 4 Hunter's End") without a full score. The easiest way is get 3-4 choices wrong when you're close in that chapter.
All achievements are correct. While there are 2 options in Chain's romantic ending, I named them the same. Perhaps, I'll add an update with "Version A and B".