To me as a German, it does not sound German at all.
My guess is Spanish or Portuguese.

In wikipedia for A Prize of Gold it says: "Maria is trying to take the children to Brazil"

Brazil would point to Portuguese

In Imdb it says " trying to raise enough money to move a group of German orphans to South America"

That would either be Portuguese (Brazil) or Spanish (rest of South America).

Maybe Maria tries to teach the children the language of their planned home using songs ...