Currently in order to tell if an issue has been converted, you need to either have that view enabled, conditional formatting enabled, run a report or try and convert it and have it tell you finally it's been converted already. This is a pain. My recommendation is on the standard view of any issue in the big "Assigned To" box on the right - have a check mark graphic showing it's been converted with that being a hyperlink to the otherside of that conversion. Or a note, something. Also, in the "standard view" of the queue that the converted issues after the name of the issue have a graphic check mark next to them - like they are "done" for that part of the process. This would mean regardless of the user, settings, views, etc. they could EASILY tell an issue had already been converted.