I think you have to look at what your overall purpose is in the entirety of the story and whether your vignette fits into the purpose.
I like that you are going to explore priests who are humanly struggling with temptation to what is considered “mortal” sin or maybe even mortal sin, regardless of whether you accept it as sin, mortal or otherwise.
I also like the idea of exploring the experience of biological females in the confessional (yeah, some real horror stories exist, including challenging the medical opinions of ob-gyns).
I would caution though in dealing with the priest’s behavior to not cast the priest as a… well, hmm… ideological idiot parrot. Somehow, the priest has to be a real individual wrestling with having to state centuries of teaching based on long held Biblical interpretation and hierarchy teachings in a cogent argument even if he himself has a crisis of faith because of some past issues.
Also, explore the seal of the confessional, both to understand it in great depth and to possibly use it to add a bit of dissonance and discomfort at some portion of the story.
Hope this analysis helps and any criticism is gentle enough!