Currently, the system does not stop a user from adding approval workflows to tasks or issues within a project that is already in Completed status. Email notifications do not go out and approvers are unable to log their approval or rejection. It would be nice to have a hard stop with a descriptive error message:
The project status cannot be changed to 'Complete' until open approvals are completed (and list the objects with links needing approvals)
The approval process cannot be attached because the project status is in 'Complete'