I've added code to display these totals, with the following caveats:
- The total number of authors listed is the actual number of individual authors. For example, if you catalog Killing Lincoln by Bill O'Reilly and Martin Dugard, that counts as two authors, even if you have no other books by either of them individually.
- The total is displayed at the top level of the TOC for Authors, Titles, Series, Genres and Descriptions. It is not displayed for Recently Added.
- Totals are not included when generating MOBI catalogs, as the Kindle display engine shows totals (calculated differently) in its Periodical TOC. It's too confusing to see two different numbers displayed in the TOC, and I can't control the way the Kindle computes its totals.
The revision will be submitted for inclusion with the next release.