How can I check that BookyAI really learned my voice?

In the "Author voice" card on the Authors page (version 1.9.18 and later), type a topic in the box at the bottom, or leave it empty, and press "Hear my voice". BookyAI writes the same paragraph twice, side by side: "Without your voice", as any AI would write it, and "In your voice". If something is not quite you, add a correction under "Correct it in your own words" (for example "less polished, I write the way I talk") and press "Hear my voice" again. You can also edit the voice guide itself: it is plain text, and "Save guide" appears as soon as you change it. The expressions found in your writing are shown as small labels; remove the ones you would not want to see in a book.