One thing should have been obvious to me but apparently it was not. To even get the whole thing going one needs some momentum besides a few encouraging comments on the forums. Mirabelle is a mere stranger in Niselur with no IG history. She would first need to build some reputation and credibility.
If Niselur needs a new religion, they are perfectly capable of making it themselves. I do not seem to have the time available for the effort required. Thanks to all who contributed.
I really hope you continue on this but its of course your decision. Two things, you don't need that much credibility as you could simply request a lordship to found a religion, I have seen it done before IIRC, and I doubt Niselur could just come up with a new religion if it needed one. Your ideas might not be perfect, but they are good and I hope you continue on with this.