I’was facing problems with installation of  Joomla 1.5.9 and Community Builder 1.2 in German. For both the language packs exist, but these does not seem to work properly. I installed the (old) Joomla German Language pack and it worked for me. After the installation of Community Builder (CB) I recognised, that it should be translated also. After the installation of additional language I faced the problems described here. Even after the installation instructions provided in that site my CB remains English. (CB is completely localized and the template variables are replaced by the words from the localization file).

See comments for the resolution.