I’ve got the same problem (wordpress 4.3.1) and also with the translations in Dutch. Did you find a solution for this yet?
No, still no answer. In the meantime I’ve purchased the UPME (User Profile Made Easy) plugin from codecanyon.
The translation strings you mentioned are in the translation template (.po file), however, they are marked as “fuzzy”. Fuzzy translations are not processed as part of the machine readable translation file (.mo) which is what handles the actual translation. Unfortunately, since I do not speak the language, I am not able to review the translation files to validate these strings (but that is something any user can do either for their own use or to contribute back to the project).
Very soon, that will be even easier because wordpress.org is in the process of moving all plugin translations to be handled by https://translate.wordpress.org/
The wordpress.org plugins team notified me that WP-Members is scheduled to be imported next week.
At that point, language packs will be available for the plugin from wordpress.org, and at some point in the near future, I’ll stop shipping translations with the plugin.
The good news is that this translations will now be able to be managed by the polyglots team.