How would one edit a custom workflow status that was added via the Set Workflow Status action ?
This article doesn't address it: https://help.nintex.com/en-us/nintex2013/help/Workflow/RootCategory/Actions/Nintex.Workflow.SetCusto...
What do you mean by edit the workflow status? Why would you want to modify this since it shows the status of the workflow for that list item? You could remove it from showing, but again not sure why you would need to do that.
What you can do is create a separate metadata column for "work item status" which you can then put whatever values in to show their progress. I tend to do this myself to create my own status fields for different processes so I can keep up with them.
@jval604 do you have 10 minutes for a quick zoom meeting so I can see what you're trying to do. May be a quick and easy solution.