Before this ticket gets assigned to my colleagues, I will try to help.
The proper way to translate strings depends a lot on how they have been implemented inside the theme/plugin.
Sometimes, there are even duplicates of the same string and only one of them is the correct one that needs to be translated.
Also, sometimes, simply removing the string (checking the box and removing it) and then re-registering it again by scanning for it (one of the methods below) and re-translating it resolves the issue.
1. Please try this:
Go to WPML > String Translation and at the bottom of the page you will find a checkbox called "Look for strings while pages are rendered". You can enable (check) that and then go in the front end to a page where you have that string showing up and then go back to WPML > String Translation and search for that string and see if it now shows up.
2. If you can't find them inside the WPML > String Translation, they might be added as admin text.
