My best advice is to give her space and time. She will come around on her own. Most people do.
And at the risk of sounding like the devil's advocate, I don't see what you did wrong. At least not 100% wrong. More like the way you said it was wrong. You gave an opinion and a suggestion as a fan which all fans do with fiction. It comes with the territory. Fans even make fanart and even fanfiction that deviates from what the author had in mind, but the professional thing to do is to just take it as flattery that people are making fanworks in general of their work and move on. The only case of which an author is justified in being offended and banning someone is if they're making fanworks that are problematic for good reason (underage porn for example), they're plagiarising or they're claiming your work is theirs or are openly insulting the author. You shared an idea and gave criticism. They way you said it was wrong, they way you're acting is wrong and honestly, some questions and some things are best kept to yourself out of respect. The author doesn't owe you anything.
Perhaps she reacted this way because she lost her pet and was in a bad place, so I would not take it too personally. You apologized sincerely and did right. And she doesn't sound like a bad person. She just sounds like she got a negative criticism and reacted badly to it. Now, I'm not saying you're not in the wrong either, friend. There is a way to give criticism and suggestions, but being a know it all is not polite and I can tell you from experience that telling a comic author you can write their story better than them (even if not in those words), is not very nice. Does it merit banning? No. We all say dumb things. Moreover, making multiple accounts just to apologize to someone comes across as a little creepy, so it is in fact counterproductive.
In my experience, neither of you are toxic people. You're both good people who each reacted badly to a tough situation at a bad time. However, it can turn around. Stop making multiple accounts and leave her alone. As for her, she needs to sit and really think about what she was getting herself into when she became a comic author and put her work in public. She has to accept that some people are not going to agree with how she write or point out mistakes. When she does, she going to give you, and herself, a break.
EDIT: I cleared the air on some points because they sounded contradictory.