cornerstone error

Hi i have a problem on this website https://www.meridianocongress.com, where i put the cool timeline pro plugin. I thought it was a problem relate to cornerstone editor so i wrote to its customer care giving them an admin access on our sandbox. They have checked it and they found that the error is related to your plugin :

PHP Fatal error: Call to undefined function get_fa() in /wp-content/plugins/cool-timeline-pro/includes/views/horizontal-timeline.php on line 210

Please tell me if it is a known bug or if you need to enter the backend to check it too

Best Regards