Perhaps the robin’s got a taste for the finer things in life and has become extravagant.
Robin should be a proper noun in this sentence, right?
I would suppose the translation should be something like: "Robin’s taste has become refined, and she has become more extravagant, hasn’t she?
@ericaw
As you explained, the JPN-ENG pair doesn’t match. And “the robin’s” is just a typo, which has been already corrected on Tatoeba.
口が肥える is used strictly in the context of culinary (food and/or beverage) while “have got a taste for the finer things in life” in English can also include clothing, jewels, art, furniture, etc.