Try reading the novel it have better explanation (●'◡'●)ﾉ
There wont be any retribution, Im afraid. Aria is purely a villainess caught up with her revenge because of her past. Hmmm but I guess since Mielle did try to kill her, even in the present life, that she's only giving back the misfortune she got? Its indeed unfair because she had two huge advantage - her power and her knowledge.
I cant really categorize her actions as anything other than revenge. But at least she sort of tried to better herself with those knowledge; she did prepare everything to avoid the future she dreaded.
I'm conflicted of what the author wants Aria to be. If the author wants Aria to be a villian, then yeah I can see that. I don't support her actions and sometimes I honestly feel like she's going back and forth with her character, it's like the author is not sure whether she wants the reader to hate her or like her. Sometimes I think that..oh the author wants us to feel bad for her, but I don't. Yes, she suffered previously but do I condone her actions? NO. Mielle on the other hand is supposedly Aria's rival in this, but her character lacks so much depth. She was molded into the stereotype of 'all rivals are dumber than protagonist'. Just planting a rival for the sake of it.
While reading this, all I wanted was Aria to develop into a better person. I'm hoping she will get her retribution later in the chapters because she deserved it as much as Mielle does. If the roles were reversed, she's doing exactly what her sister is doing in the end. If there's no such ark, the whole story becomes pointless and is only glorifying her actions. We are forced to sympathize with her and understand why she's doing all this. Hoping the story is headed this way...