If using csv or simplecsv as format, the language parameter controls how date, time, and decimal values are formatted during export and parsed during import.
For exports, the language parameter controls the language of the column headers, except for custom fields. Additionally, human readable descriptions for certain fields are exported in the selected language.
As default, the language from the program settings of the administrator used for the API call is used.
Can be one of de-AT, de-CH, de-DE, de-LI, de-LU, en-AU, en-CA, en-GB, en-IE, en-NZ, en-US, en-ZA, es-AR, es-CL, es-CO, es-ES, es-MX, es-US, fr-BE, fr-CA, fr-CH, fr-FR, fr-LU, it-CH, it-IT, pt-BR, or pt-PT.