Well, the only mention of monastery in the thread is OP mentioning my game [...]
I named if more as a generic marker, than to target actual monasteries, and obviously not to point to your game.
I just found it funny to see people idealizing what being a religious person could be in the past, imagining some kind of perpetual Spanish inquisition, while the reality was often way more lax than this.
Though there are texts from a 14th/15th century abbot in the game. What you talk about could possibly end up in some of his writings.
If you need a corruption factor, there's tons of things that your Abbot could have wrote.
Priestly celibacy date from the XIth century, but it's alleged that popes like Julius II (1503-1513) or Paul III (1534-1549), had children while being in holy orders. Alexander VI (1492-1503), father of Cesare and Lucrezia Borgia, is assumed to have been still sexually active during his pontificate. Then you've Paul II (1461-1471) or Leo X (1513-1521), who were also sexually active during their pontificate and also gay. Your abbot don't lived at the right time to have known them, but if popes where acting that way, it's not difficult to understand that there's Cardinals and Bishops who weren't saint either...
Later (late XVIth, early XVIIth), but still interesting by its process, Richelieu, main advisor of Louis XIII, entered in holy orders because his brother decided the become a monk instead of being bishop of Luçon. The bishopric was in the family since two decades, and had to stay in the family, so Armand Jean became bishop, then later Cardinal. I named it because Richelieu is a know historical figure, but the more you goes back in time, the more frequent are those case of people entering holy orders not by vocation but due to familial interest. And when you don't have the vocation, it's easier to not follow the rules...
And of course there's all those cases of women sent to the convent because of their sexual behavior.
There's really interesting thing that your Abbot can have wrote about, and all can lead a modern time nun to become a realy slut. This even against her will if needed; after all, this is the tradition of the clergy, and traditions have to be followed.