Hi Utnik, I know it is not related to orphans and widows, but it helps to understand typesetting in general and particularly for books. If you want to know more about book design and typesetting for books, it might help to read books from Prof. Reuß in Germany (for example »Ende der Hynose — vom Netz und zum Buch« and »Die perfekte Lesemaschine — Zur Ergonomie des Buches«). I don't know if these titles are available in English though…
If you modify the tracking (space between words) and will give it a certain range, the hyphenation might be better (depending on the language, text and font), so that the very last line would remain on the page and not be moved to the next one. Nobody said that book layout and book typesetting is a simple task. 3 minutes »YouTube University« won't take you to the spheres of being a master

That said, don't think that i.e. Affinity Publisher is flawless or easier to handle. Anyway, have fun with Scribus, it is a joy to work with, and every time the printer hands me the print product I am delighted and proud of the result.