I am seeing the PROCESS_CANCELLED and PROCESS_COMPLETED events to be configured as event types in Activiti guide under the section 3.18.6. Supported event types.
But I am not seeing the same event types in Event Listeners tab of a process. I am planning to use the above listeners to build some listeners which is specific to my requirements.
About the missing event in the UI, you could add a new JIRA issue. (don't forget that an open source software will happily accept contributions from the community members )