What shortcodes work inside an Episode Credits template?
Any shortcode you can use in episode content works in a credits template. Shortcodes are resolved at the moment you click Apply — the result is what gets saved, not the shortcode itself.
This means dynamic shortcodes like [benecaster_recent_members] capture current data at stamp time. Listeners who hear the episode six months later will see who was subscribed when the episode was created — which is usually exactly what you want for recognition copy. If you want a live-updating list, put the shortcode directly in the episode body instead, where it renders dynamically on page load.