First, I'm pretty certain that sentence about Hiro goes beyond Chapter 3.
I reread the text and didn`t find what exactly goes beyond chapter 3. nevertheless I am ready to remove part which you consider as spoiler. As a temporal measure I used spoiler tag to cover it.
Your reasoning with Celeste is extremely weak. If she was a "master strategist" then she would have been able to read peoples moves ahead of time and been way more dangerous than she was. But, she did a horrible job of using strategy, and was horrible at acting as well. Everything she did in the trial was just pathetic. If everyone wasn't just letting Makoto solve things for himself, she would have been called out immediately. She showed only a talent for keeping up a poker face in her plot. No manipulation (Yamada was already ready to eat out of her hand before this), strategy, and no calculation. Nothing. Just, "lying". AND EVEN THEN....she was much worse at it than she had shown talent for in the past. I'd sooner believe the luck thing was real than she actually had any strategy. Also, luck can get you out of any situation and win you any game. Luck overthrows strategy, even in a game based on strategy. If you're just making all your moves on a whim, but you're blessed with intense luck, it will seem as if you're "reading the other player". But, in all actuality, you're just picking all the right moves.
She tells. that she wins by luck, but it is an obvious lie. There is no way to win by luck in shogi
. There is no luck - just strategy and mistakes. She also likes othello - another strategy game. Same goes for professional gambling - victory there is not random, but is determined by a good strategy and calculations(yes poker, yes slots, yes blackjack). And strategy, calculation and lie had to be her talent. The problems with her are not problem of strategy, they are problems of realization of this strategy. Her plan was perfectly planned, but poorly executed. Make right decision and do it is too very different thing. Kill someone is not as difinitive as take a piece. And she is not an ultimate killer. If not some random mistakes - she would be beyond reach, and "I always suspect her" wouldn`t roll in trial.
There was not manipulation, he already ate from her hand
is not an answer - why he eat from her hand IS result of manipulation and it was not enough to make him murder someone (or any other - there was not motive and nobody else was able to make someone an accomplice, taking rules in consideration). I am not yet ready to siriously discuss trial, but all her actions beyond this were within borders of character.
I am telling what someone being a "moral compass" implies. Maybe it's different where you live? I dunno, but if I called someone a moral compass, it would be because they led people in the right direction, and it'd be the same for people who live in this area. It doesn't matter what the definition of a "compass" is, that's just how sayings can work.
I guess we may agree that sayings can work different for different people : ) And don`t forget, that usually he operates with support of school administration.