I agree that would be nice, but unfortunately I don't know of a way to see what the original name of a renamed action was. I've even used PowerStudio to view the full JSON, but it only shows the name you give an action if you've renamed it. The one way I could see to find it out if you don't know it, is to click the little i (info) icon on the action in question, go to the Learn More, and search for the text that describes that action to see what action it was.
As for a "list" for documenting a flow, you can view the full JSON by using the Get Flow action (e.g. in a separate flow) and view the output of that action. Does that help at all...?