First screenshot shows that Flyspray doesn't handle failed sending emails at all. Someone should address that, probably by catching the exception(s) and
handle them properly.
These errors probably never happen in most Flyspray installs (so no prominent issue yet) where SMTP settings are emtpy or localhost/
127.0.0.1 and local mailserver eats every mail first and later independently of php/flyspray request it sends emails and handles later errors or bounce mails. (in my understanding, correct me if I'm wrong.)
In your case something blocked the connection.
https://stackoverflow.com/questions/36695327/swiftmailer-connection-refused-111 seems about the same error code from swiftmailer.
I also tried to reproduce
https://bugs.flyspray.org/2449 and found my hosting blocked outgoing smtp. They just wanted using the local mail server/localhost for script probably.
Maybe a similiar problem in your case?
With
https://github.com/Flyspray/flyspray/commit/eae68ff63b2622f977455dd0a3c1bef459e514a6 at github master branch I brought back the FS_MAIL_LOGGING feature, so by editing the define('FS_MAIL_LOGFILE'...
in includes/constants.inc.php can maybe shed some light to that issue.
The 'Test' button in the admin prefs area only tests the saved email configuration, not the values when editing the form. (a little usability issue i know, just a little helper for quick checking)