Anything that involves lots of men and/or heavy weapons is doomed to failure
Hardly.
Unless severely damaging a city, and causing heavy casualties to the native forces thereby creating panic in the country is failure in your eyes.
If no more surprise attacks are possible, or if the unit is getting close to having its secret location discovered it can be extracted by the KM or Japanese navy. That way there are no dead bad guys to show the press.
If the unit is equipped as I listed then it would be a huge task to take them out.
As long as before they intiate their attack the commandos make sure to establish themselves around the targeted city, placing watch posts at each entry road and a good central hiding and defensive position, they will have a huge advantage. Commandeering cars from natives the night before the attack would be very smart as it will provide a good getaway option.