Saying she's improved comes over as a backhanded compliment.

说她进步了是一种挖苦的恭维话。

《柯林斯英汉双解大词典》

That's rather a backhanded compliment.

那倒是一则讥讽的恭维话。

youdao

Attacks from that source amounted to a backhanded compliment to his integrity.

那种来源的攻击等同于对他正直品质的间接赞扬。

youdao

Once again, almost as a backhanded compliment, the home fans burst into their Brodeur chant.

WSJ: NHL Playoffs: New York Rangers Top New Jersey Devils With Rope-A-Dope Act

In the coffee houses of Lvov, optimistic Galician intellectuals see all this as a backhanded compliment.

ECONOMIST: Ukraine

To Mr Heinapuu and his pals, the Russian ire they arouse is a backhanded compliment.

ECONOMIST: The Finno-Ugrics