Going out of waitlist doesn't send a confirmation email

Please double check this. Perhaps the second email was trapped in a spam filter. I ran your Steps to reproduce in a test system, and it worked perfectly, with the second confirmation email sent as soon as the auto fill completed. The emails are sent to the registrant.

Yes now shift from waitlist to compelte is working on Cancel or Delete of the registration... And mail sent too. So strange, maybe the last drupal update, or some registration settings I mistaked on !
Thanks

Thanks for letting me know things are working now! Glad it worked out. Email delivery can be a little tricky at times.