Crons are running but System Status is No cron runs have been recorded
Did you check if the cron run is recorded if you call that url manually?
That way you eliminate the possibility of having a typo in the url or an invalid site key.

Some steps you could follow:


is 'curl' installed on the server that executes the cron run?
in the access log of your webserver, do you see the url being called?https://example.org/administrator/components/com_civicrm/civicrm/bin/cron.php
when executing the command from a terminal, do you see an error, for example about an incorrect site-key?
do you see an error message in the website log? (I don't know where Joomla stores messages, in Drupal there is the Watchdog log)