I don't see why a nun waifu necessarily has to be a corruption arc any more than Simmone's story is a corruption arc
Well, maybe take another look at it then.
Simmone´s story is an seduction arc not an corruption arc, because Simmone´s not planning on staying solo her whole life, so the MC is an option, he could be just that guy and Simmone could be that one girl for him, you never know, so its seduction. MC would, simply said, trying to put himself in top position in the "Race" for this girl.
On the opposite, a fully commited faithful Nun (not the sexcult ones) isn´t planning at all for any man in her life, she declines any "Race" for her. MC would derail her faith an life-planning for short-lived personal pleasure, that would be an corruption arc for sure, especially in these kinda games.
There´s a difference between seduction and corruption.
I have only superficial knowledge about Julie d'Aubigny, well...... none of us were there to see it live

but if i had to guess i wouldn´t bet that she used only "seduction".
But to be fair, unlike in real life, in this games there can be a lot of different kinda "nuns" so.....all of this wouldn´t be applicable either way....