Do you trigger COP reset intentionally or is it some undesired unpexpected event? If 2nd, then you can only fix you FW, so that COP doesn't happen. When COP times out, it is too late to shut down MSCAN. Not only CPU, but also all peripherals including MSCAN are reset, so any ongoing transmission from your MCU may be abrupt cancelled in the middle of message, leading to some CAN errors.
You should make sure MCU CAN pins are pulled up and not floating when reset occurs.