As of TS2009 (not sure about before because I never did it), these are all supported in the config file according to what I got from TrainzDev and somewhere else.
Standard and used for English:
username
description
Used for Chinese:
username-cn
description-cn
Used for Czech:
username-cz
description-cz
Used for German:
username-de
description-de
Used for Spanish:
username-es
description-es
Used for French:
username-fr
description-fr
Used for Italian:
username-it
description-it
Used for Dutch:
username-nl
description-nl
Used for Polish:
username-pl
description-pl
Used for Russian:
username-ru
description-ru
--snip