Currently there is no way to tell that a workspace or custom transformer stored in a repository has any history without selecting it (checking the box to the left of it) and then hitting the History button at the top of the page, or hitting History and then browsing/filtering the commits. An improvement would be to add an icon to the right of the workspace if it has history (like the star for favorite and binoculars for View Workspace), and allow the icon to be clicked to open the History dialog for that workspace.
Might I suggest using one of the official Git logos: https://git-scm.com/downloads/logos, such as:
or 
(or even a pale grey version for when no history exists, and the black or orange one when history does exist).