I was wondering if Andelina could be considered a Mary Sue, or at least she could have been back in the day. I personally think not.
RELATIONSHIPS- After all she was a cheerful, yet wild kid, so her relationships are quite normal. She's loveable to many in general, nice for characters her age, and annoying to some adults. She had bonds with both good and bad sides, that's right, but since she was dismissed from the evil side as any kind of henchman, it was just normal she'd end as a friendly neutral character. She isn't going to fight against the N-side, and there's not interest from the N-side on using her against the heroes. She is just there living her life with who symphatizes with her.
Also the fact she is a princess at the tribe, I like to think it was justified by her background. It doesn't sound too crazy that she'd end in the beach like Crash in the first game, but being found by the natives and earning her place. Although maybe being princess could be considered too much.
OVERPOWERED- About being overpowered... I never conceived her as being more powerful than your average mutant. She will occasionally go crazy, but a skillful bandicoot could jump on her head enough times to knock her off. Her super strenght is pmuch just a mutant plus, I'm not sure if it is too much. And the fire magic, true is we've seen Papu Papu using magic before so it's normal her attendance to the school would boost that, in addition with her pyromany.
FOCUS OF DRAMA/ATTENTION- What would bother me is her heart problems. It justifies that she is left to live with the natives rather than being adopted back by the villians, that would be less 'bond-taking', but deffntely it was always an extra that she could go without. Some extra drama. Of course it was out of place in the Crash bandicoot world but that detail was added as a thing to be part of the Academy of Evil AU, where there was extra drama already, so... there's a blurred line, isn't it? It gives her the feature of having panic to hospitals, that could be character development, away from being fitting or not. But too much character development?
SO... I think the biggest Mary-Sueish traits about Andelina are the large amount of traits she has. Maybe too diverse. I consider every character should be relatively well summarized in a theme, and if Andelina's was 'fire', the heart disease maybe would be too much. I think in the future I'd take away that drama and make her attend hospitals to take care of her pyromany. Much easier to understand of a character in few words, so would leave much way for development since it'll be clear what it's 'new' and 'a twist' for her. Her relationships, I think would be fine, since the type of character she is kind of works with having many symphatizers.
And yes, I know what you came in from, and you had your reasons... Here I go: if you are missing me talking about N. Igma, I'll say it now: I'd change that the most- leave her as a comical stalker. A little late for give it any kind of an use, but if I was to go back in time to the AoE days: Comical stalker. No lover. It seemed a good idea at the time for me. But if I was more mature at the time, I'd would have quickly dismissed the idea of they being a ship and leaving their relation in a comical and maybe friendly stalker/poor lonesome man. More efficient and emphatical.
So basically I'd leave Andelina to face dramas from other sources than herself. I'd leave her as a very cheerful funny character. The drama depth I gave her, I'd let her have it by facing drama and sad times with optimism and maybe heartbreaking naivity, instead of making her sad over stuff or give her something to suffer about, that went away from her 'child' idea. If I was to leave the drama of the heart disease and that stuff, I'd deffintely do in another kind of story witha determined role
So TLDR: I don't consider her a Mary Sue, but deffintely I'd make some adjustments to make her a less overtraited character, all to make her better.