Translation:Whose bread one eats, that person's language one speaks.
In every other language I've studied, both here on Duolingo and in a classroom setting, the practice has always been to translate a proverb into a proverb of the same meaning in the target language. For example, in English we have the saying "It costs an arm and a leg" which means it's very expensive. If I were to translate that into Spanish, I would have to say "Cuesta un ojo de la cara" which has the same sense but literally translates as "It costs an eye of the face".
In a similar fashion, this Esperanto proverb should be translated into English as "When in Rome, do as the Romans do".
There is a feature in Duolingo that lets the creators of a language course put proverbs and idiomatic expressions into their own skill category that can be added to one's learning for the mere price of a few lingots. I would suggest doing that for Esperanto as well.
I don't think the meaning is the same though. "in Rome..." means it is up to outsider to adapt to one group's codes when joining it. The bread thing means that you'll be inclined (by force or by will) to follow the ideas of and viewpoints (or at least defend them) of the person/group who helping you when you're in need.
There two closely related Czech proverbs. One is pretty common( and I think it has an English equivalent as well) Kiu volas esti kun lupoj, tiu devas krii kun ili. I feel this is close to this sentence's meaning. But there apparently is another proverb very close to the German one with a slight twist: Kies panon vi manĝas, ties kanton kantu. The meaning is more like "be grateful and shut up" :-).
No, the closest translation we have is related to the English expression "when in Rome…" ("à Rome, fais comme les Romains") and comes from the same origin: https://fr.wiktionary.org/wiki/%C3%A0_Rome,_fais_comme_les_Romains
"Autre pays, autre mœurs" ("other country, other customs") is a bit different in meaning, but more common.