I think there was enough 'Andalite arrogance' in her psychotic outburst shortly after Ax discovers her labwork. If you overlooked it and need a quick review, it's on page 122, where she gleefully exclaims that her creation isn't just about defeating the Yeerks, but gives the Andalites absolute power to destroy any who oppose the Andalites and all 'enemies of decency and goodness.'
She then is told that she's been going to be killed after the mission to keep the details of the mission secret, which somehow leads her to the conclusion that sacrificing humanity isn't worth it to destroying the Yeerks... wait, how are those thoughts connected? Anyways, she gets wishy-washy over "Go against one of my own, or save the human race" in the Yeerk pool, and in the end decides to stick with her new moral outlook: It isn't worth defeating the enemy if the cost is the human race, because the humans are good and decent... but she never repents of the idea of wiping out everyone who opposes them.
I'm going to vote 'Badly Written' but only because of the "Well, risking other intelligent species is OK if it is necessary to stop the enemy, I'll see the mission through... wait, I'm going to die? Then in that case it isn't worth risking the species." It isn't even cowardly, because she isn't planning on opposing Arbat to save herself, it is that somehow ending the mission by killing her made her realize that wiping out humans is 'foolishly, criminally wrong.' What?
I wouldn't consider her Mary-Sue, because she's got flaws and strengths, but maybe it would have been better if she wasn't a super-talented tail-fighter since it wasn't strictly necessary to gain Ax's respect and admiration and then she really would be just a prodigy, gifted but not Mary-Sue.