Templates (cptl files) are not recommended for use anymore. I am aware of the fact that the word ‘template’ is often used wrongly. What you mention are cptx-files which may or may not have a solid Theme, but you can use them as example or take out slides, the same way as you can use the Quick Start Projects (and the same projects here in the portal) and Ready-to-go slides from the Assets panel in Captivate.

Having fully functional Themes (for design) completed with a Library of Shared actions and JS snippets would be the ideal solution. However I am not aware of anyone offering that. Will not comment more.