Can I tell the AI what my Glossary, Preface or Acknowledgments should contain?

Yes, from version 1.9.15. In the manuscript list of the book, move the mouse over the section and click "Instructions". Write exactly what the section must contain, in what structure and how long, for example "Only the 20 most important terms, as a table: term, plain definition" or "Thank my editor Ana and the Thursday writing group; keep it under 150 words". Click Save. Instructions are followed exactly the next time that section is generated or regenerated, and they win over BookyAI's default length and structure. Saving them does not rewrite the section: click Regenerate on its row when you are ready. The previous text is kept in Versions.