Adding a custom subject field to the Revision Information Drupal 7
No - because revisions are not Drupal entities themselves but metadata associated with entities. You can expose an entity to the revisioning system but not the other way around, its a core part of Drupal. 

Best way I could think of to come close to this functionality is to have a special fieldset / field collection of fields that allow for what you want (ex. log message, subject) and then use field permissions to hide that from the end user. You would then have your team use these fields for recording their updates rather than the log field.