Hey Nick,
One way to do this would be to update the language files on your site.
This snippet will change it across your entire site:
add_filter('gettext', 'change_tickets_text', 10, 3);
function change_tickets_text( $translations, $text, $domain ) {
// Match the text you want you want to translate, preferably also match the text domain
// The custom text you want instead
$text = str_ireplace( "Organizer", "Organiser", $text );
return $text;
}
Yet another option would be to use the Say What plugin.
Let me know if these options will work for you. 🙂
Cheers!
Geoff