Glad you noticed that! It was a conscious decision, not the translation model improvising. For ech language, we only use a local happiness related bird proverb if it’s genuinely attested in that language, and when one exists, we add the extra paragraph explaining it. Where no such proverb exists, it falls back to a translation of the English “happy as a lark.” So French, English, and German have their own, while others fall back by design, not by model error. And yes, all of them nod back to the Hungarian proverb that started this whole thing.