While I completely understand the desire for stronger punishments for Akatsuki, they are likely protected by rules in place to actually protect adventurers. First of all, adventuring is a dangerous profession. Adventurers regularly risk their lives as part of the job. It has good rewards, as a result, but it has a lot of risk. So there are probably many times when adventurers have faced situations where at least one party member is likely to die, and the others would need to abandon them if they want to avoid the entire party being destroyed. Also, if one party member can't go on, but their gear might increase the odds of the others surviving, then it would make sense to allow them to take the equipment. After all, the goal for the Guild is for as many adventurers to survive as possible. They wouldn't have rules set up that would place more burden on people doing dangerous work for the benefit of so many. Clearly, this instance is an abuse of those rules, but not in a way that would be likely to be able to be codified, and thus be punishable.
Second, the laws of the land would probably also not carry punishments for that. After all, the nobility and royalty would see adventurers as a valuable resource for fighting dangerous enemies, and also see them as a fairly expendable force, in the first place. In fact, if an adventurer becomes too strong, and the nobles or royals fear they might seek more power, they might even try to send them on dangerous quests to get them killed off (with promises of great rewards and possibly "accidentally underestimating" the difficulty as incentives for them to take it). So they wouldn't want to punish more adventurers, when already losing at least one, because while they might be expendable, they still are fairly valuable resources.
Third, the involvement of the noble in the quest makes it more difficult for them to punish the adventurers. After all, he was their client. So they have to protect him, which is more difficult to do if having to drag her along, and if he tells them to leave her behind, they are also supposed to be obeying the orders of their client, along with the fact that it becomes more difficult to go against the whims of a noble (especially one that was indicating to be fairly high ranking).
As for the Guildmaster, there probably are rules set up for punishing the manipulating of ranks, but they wouldn't likely have jails the way we do, now, and would probably think that stripping a Guildmaster of his position was a significant punishment. Also, with it being a more powerful position, it is easier for that position to get lighter punishments compared to others, anyway. We see that around the world when politicians (regardless of country or political stances) break the rules they give others, and get only light punishments (or aren't punished as long as they give apologies) or celebrities get much lighter punishments or "home arrests" for breaking laws that would have regular citizens in jail for years.
I will say, though, that I'm happy that they didn't go for her being physically assaulted. It seems that often gets used in stories, as an easy way of garnering sympathy or producing drama, but I can't think of a situation off the top of my head that has resolved it well, and it seems like it often makes light of how serious that is in real life, and the lasting trauma it can cause. There should be other ways for stories to create drama and trauma, besides that.
For those that are wondering why her experience would make men less likely to approach her, without the other part (and that are still reading this), I think it makes sense. They assume she was in a relationship with one of the members of Akatsuki. So even without assault, her assumed romantic interest took advantage of that, and her lacking more of a place to belong, to take advantage of her and drain her of money and energy and life, and then abandoned her to die in a dungeon.
So now we see that others care about her, and they want to protect her. They want to provide a place that she belongs, but the last person that said he wanted to do that for her was helping to manipulate and abuse her. They don't want her to think they are trying to do the same. So they try to show they care about her as a person, that they love and respect and cherish her, and they don't try to get into a relationship with her, because they don't want her to think that they were just pretending to care about her to get her to let her guard down, so that they can get something out of her. She's already lost her place that she belongs twice, and they are afraid that if they get too close, she will be afraid to get her hopes up, and will pull away instead. They care more about her mental and physical well-being, than they do about furthering a romantic relationship with her.
All that said, I hope that the members of Akatsuki do end up dying in dungeons or some other way for how they treated her. The legal system and the guild system might not have a way to punish that while also supporting adventurers that take risks to make things safer for everybody else, but that doesn't mean the author can't dispense justice instead.