Yeah, but after stepping in to stop two execution orders you'd probably consider that your fiance's justifications for wanting your sister dead maybe aren't on the level, and you shouldn't glibly parrot them back to the person trying to help you save her.
The thing is, the "rumors" about Karina as the Princess Consort included being frivolous with money, lavish social parties, various overbearing demands of nobility, and so on.
Those are things that Karina herself refers to by more "tempered" terms all the back in chapter 1, but the accompanying illustrations on those same pages show her acting as one would expect a "conventional villainess" to act--domineering, materialistic, and so on.
The operative context, though, is that Karina was doing all of this because of the people who approached her, seeking favor, telling her to act this way, speak like that, and so on. We get that in various other flashbacks of her remembering interactions with nameless nobles, and it creates a picture of Karina being fed one line, but then more nefarious gossip and malicious twistings of her conduct were whispered behind her back--and it seems that all of it was fueled by Orlando, who was pissed that he was given "the spare sister" instead of Aurora.
So he sought to have Karina's reputation tarnished by those with influence around the palace and kingdom, taking advantage of Karina's deferential nature in wanting to please him and everyone else and be seen as "a good queen". Some of the nobility would lavish her with praise and presents and curried favors, all while the rumor mill twisted everything into ammunition for Orlando to point at and say "see? Karina is a selfish wretch who is unfit to be queen, she must be ousted and this engagement annulled" - all so he could take Aurora's hand, the moment she was healthy enough to do so.
And
those rumors, are what Aurora is referring to. Because in a sense, they're correct--Karina acted in ways that could be objectively be said to be frivolous, domineering, and so on. But she was manipulated into doing so, all while trying to keep her head above water because the people she trusted most--her parents--told her that she had to become Princess Consort for the sake of their family's political future, and for the sake of her sister Aurora who, let's be clear, was very important to Karina at that time.
But the thing is, Aurora herself says that she didn't see Karina all that much, once Karina left for the castle. Everything Aurora heard from that point, was secondhand at best, and that would have been through the very rumor mill that was working to destroy Karina's reputation.
However, Aurora knew Karina when they were children--the older sister who read to her, who would give up her own gifts for her, who smiled at her and was always kind and considerate. That's who Karina was to Aurora, and that's the Karina that Aurora remembers, and who she wants to save now.
Even Karina's anger that's aimed at Aurora is believed to be meant for others--and as someone else pointed out earlier in this thread, Aurora can objectively be said to have done next to nothing harmful toward Karina that we have seen. Karina's
perception is what initially paints Aurora as the villain who stole everything from her, but looking at what we're shown, it's just not the case.
It wasn't Aurora who took the doll from her, it was their parents asking Karina to give it to her sister. It wasn't Aurora who stole Orlando, but Orlando himself who despised Karina and coveted Aurora, seeking to dump her the moment he could get his hands on the younger sister. It wasn't Aurora who sent assassins or soldiers after Karina, but Orlando. Aurora's direct actions that we've seen have been to keep harm from befalling her sister, playing to her latent influence on Orlando and the nobility to stymie anger or waylay aggressive action.
Because everything we've been shown of Aurora that paints her as Karina's antagonist, has been from Karina's perspective. And we've been shown over the last thirteen chapters that Karina's perspective of things is flawed, skewed, and otherwise inaccurate.
Aurora repeating the rumors' validity to Eve isn't her affirming that Karina's a villain, only that those rumors reflected the truth. They also sit separate to Aurora and her perception of and feelings toward Karina, because for her, the focus isn't Karina, Villainous Consort. It's Karina Crocus, Beloved Sister.