I was tested notifications for Translation Managers after a Translator completes a translation job, and found this wasn't working for some Managers. On checking the icl_translate_job table, I found the manager_uid column is using "tinyint(3)" so any manager user with a uid above 255 will have 255 recorded there, and the mail will always be sent to uid=255.

The manager_uid column needs to be updated to use a much larger number format to support sites with large numbers of users - eg. int(11).