It would be nice if it was possible to set a created date on the two jelly tags "AssignIssue" and "TransitionWorkflow". According to the documentation this is not possible. The problem is that if you import comments and transitions (with comments) from another system the comments get out of order because some are created with the actual time and date (comments created by "TransitionWorkflow") and others are created with the original value (comments created by "AddComment"). Finally to have the change log showing all changes in correct order we need a created date for the "AssignIssue" as well.