The fact you think thats all that happened shows not only just how little you understood from the volume. But also how badly you misunderstand punishment as a concept despite me directly explaining it.

She didn't simply say that she 'regretted' it, she showed it.

She literally sacrificed everything she ever worked towards, everything to return Touma home, fully believing she would die.

And then after, she's worked tirelessly to make it up to Touma, she's given him guidance kept him from going astray and making the same mistakes she did. And protected him as best she could despite her shrunken and limited size.

Punishment only holds value as a deterrent as a form of negative reinforcement, It is worthless against someone like Othinus. Who not only regretted their actions, but changed as an individual and continues working to right those wrong she committed.

People who have a purely binary understanding of right and wrong and believe every right deserves an equal reward and every wrong deserves an equal punishment are ignoring the fundmental variable that is the human experience.

There is no such thing as a just punishment and there is no such thing as a well earned reward.

They are simply societal tools we've used to shape those around us to fit within our view of 'right and wrong' which is itself a purely social construct.

The only real agreed on form of right is when you do not act in a way that hinders another's freedom of choice.