An email handler configured with ccwatcher=true will correctly add the CCd accounts to the watcher list but won't send them a notification of issue creation.
CreateIssueHandler.handleMessage() (also called from CreateOrCommentHandler) will create the issue without passing the accounts in the CC field and only after that has happened it will add the CCd account; this way the CCd watchers will miss the event.
I think the method should extract the eventual CCs and pass them to the IssueManager.createIssue() together with the other fields (if possible)

Best regards,
Edoardo