Probably bcuz it happened within the guild and under their responsibity. I mean yeah its not fully their responsibilty as theyre just members but getting trauma outside the guild is different from getting it within the guild ya know? And the guild operates like a small community where everyone knows each other so i guess they felt responsible for having one of their members get abused when their guild is supposed to be a safe space away from the trauma.
They became adventurers to run away from whatever theyre dealing with and the guild is their safe space. But then you hear a member was abused in the space where its supposed to be safe..? You would feel a little responsible.. especially when the abuser is from the guild master himself, who you're supposed to trust implicitly to stop bad things happening within the guild.
fully get that she has a horrible backstory but it seems like most people do in this world? why do they all spend time talking to each other about how to heal this one random girls trauma?