Since 1998, hundreds of people have contributed translations, code for new features, suggestions, and bug fixes.
The development team maintains an evolving code base from which they periodically issue releases. A paragraph in the home page downloads section describes how to use Subversion to get the latest version in development. (This can be also done by downloading the Subversion snapshot.) A contribution (translation update, patch, new feature) will be considered with a higher priority if it refers to the latest code base, and not to an ancient phpMyAdmin version.
Taking a look at the project's current list of 54 languages, we notice that they are not equally well maintained. The details about translations are available at http://cihar.com/phpMyAdmin/translations/. We can try to join the official translator for a particular language, to propose corrections to/or translations of recently added messages. If this person does not...