Hi David,
Thanks for reaching out.
The current REST APIs do not directly support retrieving this output. The generic get spool file command retrieves the agent spool files (or JES spools), but not specialized Agent plugins listings such as this one from SAP_JOB.
Long term we are planning to add this, but it is not on the immediate roadmap for the next release.
There may be some workarounds though.
Off the top of my head, the complicated workaround would be to run the command in batch and retrieve the output of that JCL, which would then reside in the JES spool. But that is not an elegant solution as it would contain too many pieces and would depend on JES delay.
We'll try to find a better way and get back to you directly if we find something.
And of course eventually there would be a dedicated endpoint for this.