This is what I had anticipated given the evidence I've found so far.
The pages we wanted to exclude are built with accordion-style markdown blocks that include dozens of listings each which go to external urls or allow a pdf download. A search returned results to one or more of those pages with no marker for where the search terms appear on the page.
Our solution is to build out a page for each individual listing in the accordion-style markdown blocks. Then creatively name the accordion block pages we wanted to exclude from search to hopefully improve the search results. They will appear at the bottom of the results list and then, if clicked, would circle the visitor back to the resource library alphabetical main pages.