The Jag does respond to every message. I know this from looking at the CAN subVIs.
On the "send" messages, it does an ACK as well. (Not sure what this is for)
You can find the Jag firmware source here:
http://www.luminarymicro.com/products/rdk-bdc24.html
or here:
http://www.luminarymicro.com/products/rdk_bdc.html
I believe what you want is in the firmware development package.