Drupal Internationalization / Translation
I don't know if I completely understand your question correctly, but I think there's some confusion. The Drupal translations from localize.drupal.org and the locale core module, will only help you translate the interface. If there's something missing or you want some custom translations you can always use: http://drupal.org/project/l10n_client - and to keep it up-to date: http://drupal.org/project/l10n_update

The i18n module allows users to translate the content into different languages, but it does not auto-translate. There are some modules that uses Google's APIs to auto translate but one violates Google's TOS and the other one will stop working when google pulls there translation API


http://drupal.org/project/gtrans
http://drupal.org/project/i18n_auto