Thank you so much for playing our game. It is great to hear about someone getting involved even so long after the jam. And do try the other entries, there are some excellent stories that are much more romantic than ours. Perhaps they will be even more to your taste than ARomantic Reimu.
And in response to your spoiler questions:
You are correct that Sanae is the mother of the new Hakurei shrine maiden, but I intentionally left out who she eventually marries. That was beyond the scope of Reimu's story, and picking any one character (or unnamed character) could disrupt the flow of the true ending if the reader disagreed. Perhaps hypocritical of me, as I couldn't resist throwing in a suggestion that Kogasa has a romantic fling with a kappa. I did want to show that even the girls Reimu had to reject found their own healthy, happy relationships.
I hope my Sanae writing was up to snuff to satisfy one of her fans, as she is a character I don't personally relate well with.