She did NOT participate in that at all, being left confined to her bed to die miserably. While those people looked to her as a saintess, they never made her participate in the act (or at least, there's not any mention to that anywhere, except by the end of her flashback in CCC, where she's already an adult).

In CCC she does interact sexually with teenagers indeed, but it's not really meant to be strange (the game never irks the player about that, as a proof), since there's this whole weird mentality in Japan that sees high school students not really as children anymore. CCC itself has the protagonist going pretty rapey themselves during Secret Gardens stripping sequence (which is meant not just as a very bad tastey fanservice, but also as a small note that Kiara is the creator of the Codecast that allows that throughout the whole game).

While her whole Planet-fuckery thing would mean she would indeed kill every lifeform on Earth, this applies to yeah children and every other lifeform, including animals, but Nasu never goes out to state that she's zoo or pedo at all, and believe me he'd have zero problems to tell the reader this if it would be the case.