Bucky heard 'Black Guard', it may have been in German but it didn't matter if it was in freakin' Swahili! The loyalty of mercs was measured in cold hard cash - once the money dried up so did their loyalty.
Schwartzgard on the other hand were zealous, relentless and if need be suicidal if it pleased the Red Skull. But if they could outmaneuver the teched up fanatics the payout looked twice as big. "If we take Zola and Red Skull in it sets HYDRA biotech back for months. I think the risk is worth the reward."