Can BookyAI add an illustration to every chapter of my book?

Yes, from version 1.9.22. Open the book's page and find the Illustrations card. Choose a style (Pencil drawing, Ink illustration, Children's storybook, Watercolor, Painted cinematic, Modern flat illustration or Photographic) and a placement (Across the page, Full page, or Square and centered). Then press "Illustrate N chapters". Your writing engine reads each chapter and picks the moment to draw, and your image key draws it, all in the same style. The picture is placed at the top of its chapter in every export. You can press Stop after the current picture at any time.