Would she really speak German to him?

There's quite a lot of dialogue where Carola speaks German and he always answers in English. Did she really expect him to learn German as well as all the other 'foreign' ways of the outsider? Perhaps the actor spoke English better than the character he was acting and wasn't comfortable answering in German. For Limalian, to learn German it was nothing more of a stretch than to learn English but it did strike me as odd. There didn't seem to be a lot of indication that she learned the local language. She was there for several years, so she must have learned some of it. She was already bilingual, so it would not have been impossible. They tell one another the respective words for eyes, nose and mouth, but there's no indication that either learned anything (linguistically) from the experience.

Likewise, would an Italian priest learn to use German in an African country that uses English? I'd have thought he'd have higher linguistic priorities.