WP-Members is internationalized using the gettext libraries and tools for i18n found in WordPress. The plugin’s text domain is “wp-members”.
WP-Members will run in whatever language is selected in the WP language setting. The completeness of the translation will depend upon the specific language selected.
The plugin is part of the WordPress Polyglots translation project, so all translations of the plugin are officially maintained there. Only languages that are more than 90% complete will load automatically.
Existing translations included in the plugin’s download are legacy files and are no longer maintained. They are only included to fill in the gaps when there is not a complete (or 90% complete) translation via polyglots. Once a full translation is available, the legacy translation will be removed.
A Note About Polyglots
If you are interested in providing translation either by improving an existing translation or completing on that is incomplete, please do not create a new file to send to me. ALL translation takes place via polyglots. I understand it takes effort to create/edit a translation file, so please direct those efforts to polyglots in order to have full translations there.
While anyone can contribute to translation, in order to approve translation suggestions, a user must be an “editor.” I personally have no problem requesting a user be set as an editor. However, not all translation teams openly accept editor requests from plugin authors. Some require anyone interested in becoming an editor to begin with some translation first and then be approved based on their work. Please understand the process for your specific language and translation team.