I'd like to know if @omz considers the file formats we're talking about as being stable. If so one could build tooling in other places that might prove useful.
It's not very likely that I'll make backwards-incompatible changes, though I'll obviously add things as the workflow system evolves (new action and parameter types etc.).
I'd say the format is relatively easy to understand when you pretty-print the JSON, but I don't really plan to document it properly. The workflow editor isn't really prepared for malformed data, and it's quite possible that you'll see crashes or weird behavior when you change a .wkflw file in ways that wouldn't be possible in the UI.
If you want to play with "meta" workflows, I'd really recommend making a backup of your workflows first. You can do this with my Backup workflow, which incidentally also demonstrates a practical use case of editor.reload_workflows.