Might it be helpful to seek out a Jesuit clergy member or theologian that you know and trust? It seems to me that such a person would be well-positioned to have the kinds of discussions of theology that your child seems to be seeking.
Of course, that isn't to say that you won't keep discussing things too, just that taking the questions seriously sometimes means seeking outside expertise.
I happen to know someone who might be willing to communicate with you electronically, if you're interested. The background there is not Catholic, but the theological background of the person in question is very deep and very broad; and the person has experience as a parent to an HG child in addition to that divinity training.
