So editing the resource file fixed it? Then yes I would say that is the solution, it was working correctly if it was showing the same as the resource file so it must be that the resource file was incorrect until you fixed it. Please email the corrected resource file so I can fix it in the project. joe dot audette at gmail dot com.
I would be careful about changing the default globalization to de-DE in Web.config. You must make sure the default culture has no missing keys and the only resource file I know is up to date and complete is the Resource.resx which is english. You may want to review the german resource file line by line against the english one and add the missing items. Its possible to get null references exceptions if it encounters a key used in code for which there is no entry in the default resource file.