Where are the originality and grammar checks for my imported manuscript?

In the book's workspace, click Quality review in the top-right (next to Files and Export all), or click the Originality panel on the right, which opens the same page. There you can run Check originality (this is the plagiarism-risk review) and Proofread all, or run them per chapter. Both need an AI key configured in Settings. The checks work on imported manuscripts exactly as on generated books.