She speaks fluent and idiomatic English.

她讲一口流利地道的英语。

《牛津词典》

You speak idiomatic English.

你的英语说得很地道。

youdao

If you live in England, you will soon learn to speak idiomatic English.

如果你住在英国，很快就可以学会说地道的英语。

youdao

when it comes to looking for examples of people speaking good idiomatic English in a recorded form.

当说到举一个例子说什么文本或音频材料里有使用地道的英语时，

想征服英语的话 - SpeakingMax英语口语达人

He looked dapper in a dark suit and tie and proved a gracious host, speaking excellent, if not always idiomatic, English for 90 minutes in his suite at the posh Carlyle Hotel, where a lesser-known novel by Alexandre Dumas lay open on the coffee table and a stack of European films on DVD sat next to a flat-screen television.

WSJ: Maurizio Pollini: Not as Others See Him | Cultural Conversation by David Mermelstein