That works. Thank you.
The "Cultures & Regions" and "Social issues" tags are mostly just to group together tags of similar themes for easier navigation in the browser. No actual books in the tag, only its children.
The composite column is generally to make the Book Details a little tidier-looking, but I also found that it'll also let me view all the related books on that topic (e.g. clicking on "Canada" shows books from Fiction.Cultures & Regions.Canada, Nonfiction.History.Canada, and Nonfiction.Travel Guides.Canada) without having to flatten all the tags.