What LANGID is used to extract a devices serial number?
A USB device indicates the presence of a serial number by setting the iSerialNumber field of the USB device descriptor to the serial number’s string index. To retrieve the serial number, Windows issues a string request with the language identifier (LANGID) set to 0x0409 (U.S. English). Windows always uses this LANGID to retrieve USB serial numbers, even for versions of Windows that are localized for other languages.