@Awesammon17 Hello. Thank You for trusting me with this, though I don't know if I'm the most qualified person to answer, but I'll do my best.
I think it won't matter to any readers if You edit Your work and post it again. Grammarly insists that to edit is divine, so let's trust them ;) I reedited my first work gazilion times and never heard a word of complaints from anyone. I think tis community undesstands perfectly the need to change and fix things. Perhaps, if You are worried about it, writing a short info about the edit in the synopsis would ease Your mind. I have read plenty of stories with multiple edits, so to me it's only natural to go for it.
I envy You so much that you can spot Your mistakes (if You insist there are any)
I quarrel louly with Grammarly each time it underlines any words and phrases I choose. ( I use only the free version)
I can't wait to read the prequel. You made my day revealing that You're writing it. And I apologise, but that happiness makes me not sorry that Weilan won with Your second book fro now. Maybe next month, right?
Good luck with editting and writing, both fanfic and Your book.
Best wishes
Ania