MSP430 USB Module and Baud Rate Detection
The baud rate of the USB connection has no relationship with the baud rate of the UART side of a USB to UART converter.  Regardless of the baud rate requested by the application, the data that is sent by the application will be packetized and sent over the USB connection at whatever rate the USB link is configured for (according to speed capabilities of the host and device).  It is up to the device to set the baud rate of its UART interface to that requested by the application.  The requested baud rate should come in as one of the configuration SET messages sent by the host.  

This appnote is for a different platform, but has some information on how this is done: https://www.xmos.com/developer/download/private/AN00124:-USB-CDC-Class-as-Virtual-Serial-Port(2.0.2rc1).pdf

You will have to look in the documentation for your API to see how (or if) this configuration data is exposed.  If it is not exposed, you may need to dig through the libraries to find a place where you can intercept that SET message and act on it appropriately.