We have started to work on a C# project that was originally created by German speaking developers for German users. Most of the code, including class names, comments and debug messages is written in German and so is the user interface. As one of our major goals is globalization, we decided to leave the default language to German and add language resource libraries for other languages, including English, as any other option would have turned too costly in terms of time at first.
My question is: is this a good idea, or is it better to switch the default to US English at least for the user interface like everybody else is doing? Are there any drawbacks in using a default language other than US English?