Thanks to everyone who has contributed translations to the WP-Members plugin over the years.
The plugin is now part of the worpress.org polyglots project. This means you can directly and actively contribute to the translations to make localization better.
https://translate.wordpress.org/projects/wp-plugins/wp-members
Many languages have a very good start and have numerous strings waiting for approval. Anyone can contribute suggested translations. There is still a need for many of these languages to have at least one identified editor (someone who can approve translation suggestions that are contributed by other users).
If you are interested in becoming a translation editor, you must be available on Slack: http://wordpress.slack.com. If you have an interest, contact me here and include your slack handle and the language you are interested in.
(Note: I’ve left the comments here for the time being, but keep in mind almost 100% of this information no longer applies.)