Sorting methods for custom taxonomy

I’m using the plugin to try to make an “author list” for all the contributors on our website. Normally there are a lot of plugins that can do this, but our theme actually uses a custom taxonomy where our authors are listed as “speakers,” so this one came in handy.

(A sample speaker page with no bio: https://sinaiandsynapses.org/multimedia-speaker/rabbi-ruhi-rubenstein/)

My question is: we have so many authors/speakers and only some of them are really frequent contributors. There are a lot with only one post. Is there a way we could sort the list by the number of posts each author/speaker has?

It would also be cool to hide the speakers that have blank descriptions from the list, but I know that’s asking a lot of a custom taxonomy.

Thanks! Also, this question concerns a staging version of a new theme we’re working on for the site, but all the basic structures are the same.

The page I need help with: [log in to see the link]