I decided to reach out to the creator of the novel extraction software I used. In hindsight, I probably should’ve done that in the first place, but hey, 🤷 He provided the solution!
So, for any future readers:
You can remove all Unicode characters with Calibre by following these steps:
- Select your book.
- Go to Convert books.
- Navigate to Look & Feel -> Text.
- Check the box labeled "Transliterate Unicode characters to ASCII".
- Click OK.
This solution will obviously remove bold and/or italic text formatted with Unicode, but I can perfectly live with that.