Monitor two baud rates
Your computer can not see what is going over the WiFiBoard serial connection because that connection has nothing at all to do with the connection to your computer.
If you want your computer to see what is being received on that port you must read the data from that port then send it to your computer.
It doesn't (much) matter about the difference in baud rates (only that if one sends too much data too fast for the other to forward it you will lose some data).
It's common to use something like:
while (WiFiBoard.available()) {
    Serial.write(WiFiBoard.read());
}

That will forward anything received from the WiFi board over the serial port to the computer.