We go back to previous versions from time to time. However, I believe you are right there is no way through the Editor Browse interface. However if you go to the web browser you can search or access the desired file, open it up, display history, select a prior version and then in action select open in Arbortext (assuming it is a SG(X)ML file and you should have it appear for viewing in editor. If you want to make changes than you would have to export to you workspace .
Maybe others have an easier way to do this.