I see the point that you are making. The warrant clearly states that Arochi lied to his parents about her age, and that the parents wished her a happy 18th birthday on her 17th birthday. For all we know, that may have been when she realized that EA had been lying about her age. Otherwise, I'm not sure why that particular incident was contained in the warrant.
One thing that does seem clear - EA lied about his age to the girl, and lied about her age to his parents. This to me shows that, at the very least, he realized it was wrong, but it's also possible that he knew very well that it was illegal, so he lied to cover that very fact.
MOO