Only shows ten posts?

Cornerstone adheres to your WP site’s posts-per-page setting (Settings > Reading > Blog pages show at most). You can update this setting to display additional posts per section.

Additionally, you can add pagination to your theme’s page.php template file to enable any number of a section’s posts to be accessible. A more in-depth tutorial is in the works, but for now have a look at the comments on Cornerstone official page for more information on how to add pagination for a section’s posts.