I understand your challenges completely. It's not easy to "please" everyone and fit every use case.
The "refresh" was a bad call, obviously it would only fit my scenario and probably no one else's.
My point was/is, for those who are technically "less inclined", and if they are many for some reason, the Start button not providing feedback can be a pain, because if you do make a double click in a heavy WF (with dozens or even hundreds of files listed), it's easy to create a mess. Even very light WF's can create a mess if they don't give us enough time to cancel a double or triple submission.
So my honest suggestion is, for consideration, to have the Start button change its state after clicked, like to an unclickable "Job Started" and offering something like a "<<back" link to reset it to a clickable state again.
Even better (and now just dreaming


All the best to you guys! Have a wonderful weekend