There is no single-word equivalent for fargin in English, though there are single-word antonyms like begrudge and resent. In the same way, there is no single-word equivalent in English of the French word frileux (someone who has the tendency to feel cold).
That doesn't make Yiddish or French "richer" than English; there are many words in the English language that have no single-word equivalent in either French or Yiddish. Every language has holes in it, where it takes several words to express a single concept. Sometimes languages will "borrow" (without ever really meaning to return) words from other languages when they're especially useful for plastering over those holes. Fargin doesn't cover a very big hole in English since we already have ways of expressing a good deal of nuance around the concept, ranging from merely not resenting through congratulating and on to sharing in the joy. In a sense, you could say that English is richer and more nuanced precisely because it lacks a single word to cover all of the spectrum of attitude that Yiddish packs into the word fargin. Schmooze, on the other hand, was worth