@Silfir it is in the original, and judging from the afterword, presumably the author put it in because the OC miko turned out to look too much like OG Reimu than they wanted her to be
Right, thank you! Then I guess this is feedback the author will never see. It doesn't matter if Miko-chan looks like Reimu, since it's eventually clear that she's Reimu's successor from context. (Same applies to Marisa having gone Youkai.) If anything, the ambiguity over whether she is Reimu reborn or someone else added another element of suspense, and mirrored Marisa's confusion of the heart - her head knows it's not Reimu, but she feels like she is.
At some point every doujin has to go off to the printers, so you can't always get everything down perfectly. Still, have some self-confidence!