Hi Nick,
You’re right, that’s a bug. Will be fixed in the update that will be released today.
If you want to make the string translatable meanwhile, you can replace line 556 in profile-builder/features/functions.php with the one below:
$required_error = apply_filters('wppb_required_error' , __('This field is required','profilebuilder') , $field_title);
You should know that we’ve setup a new environment for making it really easy to translate Profile Builder, without using Poedit, as well as downloading the translation files (just click Export at the bottom of the page).
It would be great if you could add your translated strings there, so that others users may benefit from them.
We’ll make sure to include the updated translation files in each new version release of the plugin.
Thank you for your help with this!
