My preference is to figure out a way to identify books with newer highlights and flag them somehow on import so Ic an manually manage the additional info.
Reason is that I will be adding additional info in Obsidian to my book highlights and then I may go back and re-read the book again and change things so I want to be sure I don’t lose my additions but also pick up the changes. Getting a second note that shows I have a new version to manually reconcile would be fine.