I was able to past a ‘schedule event’ workflow into a back end workflow, as well as the custom event it triggered without issue, or it prompting an error, although I now understand scheduling custom events does not appear available for backend workflows.
You cannot schedule a custom event in the backend - it’s not a bug.
You can schedule an API workflow, but not a custom event. If you want to schedule a custom event, schedule an API workflow which runs that custom event.
Thank you so much for the quick response and clarifying.
I should note, the reason I thought it was possible was because I had copy/pasted a scheduled event action as well as the custom event and its ‘schedule event’ action in the backend without any error.