Hi Thomas,
Your issue is is same as in any application irespective of process I guess.
I am currently only looking into Approve/Reject scenario as you might have other scenario as well.
Options
1)Ask user to select Approve/Reject status instead of button and then submit button. This allows user to avoid quick submit.
2) For addtional protection you can show the summery of data filled by user and then user finally submit.
Even after user is doing wrong selection then you cant avoid it.
Basically you want to awake the termnated/completed case again whcih I am not sure is a good idea.