May I know if this issue happens when you try to export one translation from a post? Or does it only show this error when you're trying to export in bulk?
Also, please try deactivating your 3rd party plugins and see if it works. Sometimes it may conflict with another 3rd plugin hence causing the issue.
If the issue persists, I would need to take a closer look at your site. So I would need to request temporary access (WP-Admin and FTP) preferably to a test site where the problem has been replicated if possible in order to be of better help and check if some configurations might need to be changed
Your following answer will be private, which means only you and I have access to it.
✙ I would need your permission to de-activate and re-activate Plugins and the Theme and to change configurations on the site if required. This is also a reason the backup is critical.
Also, I checked your debug information, I noticed that your MySQL version is below the plugin minimum requirements as described at: https://wpml.org/home/minimum-requirements/ . Kindly contact your hosting provider and ask them to update the MySQL version to 5.6+ for you.
Thanks!
Kor
This ticket is now closed. If you're a WPML client and need related help, please open a new support ticket.