ISO 639-1 codes will be converted to ISO 639-3 in categories and links. A list of ISO 639 codes can be found at en:ISO 639 and pages linked from there.
For use in {{Babel}}, there is a |plain= parameter which will cause {{Translate}} to output a plain, simple userbox. For example, {{Translator|spa-jpn}} outputs:
|skipcat= or |nocat= can be used to suppress all categories. If you only want to suppress categories associated to a specific userbox, use nocatindex or skipcatindex. Note that empty parameters also count: {{Translator||eng-fra|nocat1=1}} will still add Translators eng-fra.