How to translate the Button label using Pro Version

We have a french/english website. We are able to customize the Button label on the english site using the plugin’s settings… we cannot however change it on the french site using the plugin settings.

We tried overriding the .po files using LocoTranslate but that’s not working either… how can we customize the button label for separate languages?

The page I need help with: [log in to see the link]