Actually you do not need as German to take the buildings.Played J183 A Real Barn Burner, from Journal #12, with Robin (Swiftandsure). (...)
So it's one of these scenarios where one force has to quickly overwhelm a small defense while trying to slow down a bigger attack on the same objective (...)
It is enough stop the French coming from the South and avoid they can reach the farm. Imo this is the key to win easily without any risk.
As you said the French in the farm are tough. So use a large part of the German OB exchanging shots with a ML 9 force a short range is risky. It is much better avoid any discussion with those morale 9 guys in stone building and create a security belt around the farm to stop the French reinforcements . This way the scenario is less dicey (less ambushes, less CC, less short range combat) and the French cannot use at their best their besieged units. The German can instead use almost all of their force to prevent the French from reaching the farm, and the game is over since the forces suddenly become unbalanced in German's favor since the objective can remain under French control and no fight is necessary.
Of course the expert German player will set his security belt out of range or los from the "farm guys" using his long range weapons (gun and MMG) to force the French in the farm to stay down while a small concealed force (no more than two squads) will attempt to infiltrate the farm complex if an opportunity appears still mantaining a position useful to reinforce the "cage" around the French objective, the only thing the German must search.