Closed captions with triggered audio

It is possible to do what you want with JavaScript.

If it's short audio and the CC can fit within the CC box it fairly simple. If it needs to be timed to the audio and flip paragraphs, then it is a bit more complicated.

To put CC text into the container execute this JavaScript when showing the object with the audio attached.

var myCCDiv=document.getElementById("ccText").getElementsByTagName("p")[0];

myCCDiv.innerHTML="your CC text here."

So in an advanced action:

show object

execute JavaScript

assign cpCmndCC with 1

You are correct that the Closed Captioning that is available via the Slide Notes is only for audio that is added to the timeline of a given slide.

The audio triggered by an action does not have the option of using this same method of showing Closed Captioning.  However, you could use Advanced Actions an alternative method of showing text on screen (in Smart Shapes for example) to coincide with the action triggered to play an audio file from the library.  It's more work to set up, and you need to make sure the two methods don't conflict in any way, but it's doable.

Indeed, the Closed Captioning work flow is only available for slide audio, not for Object audio, nor audio triggered by the 'Play Audio' command. Logical reason is that synchronizing can only happen when there is an audio timeline. The other audio clips can play while the timeline is paused. Slide audio can be paused when pausing the timeline.

You could mimick the closed captions by creating text containers and time them to appear at the right moment, based on the audio clip. This will probably mean that you'll need advanced actions, and use the Delan Next actions command several times.