Hi Romain,
Thanks for contacting WPML support, I will be glad to help you.
Unfortunately, you can't translate this field as it's controlled by the browser and follows the language you set for the browser.
Please note that you can't also edit the original text for the same reason. Please see here: hidden link
This means that the text will be translated only if you switched the browser language. Please check the attached screenshots that show how the field appears when I switch the browser language to French.
