I say not flatteringly but with sincere conviction.

我说话不是奉承，而是心悦诚服。

《新英汉大辞典》

In a few minutes polite young men would approach, speaking softly and flatteringly.

几分钟后，一名有礼貌的年轻人出现，轻声细语，甜嘴蜜舌。

youdao

Thankfully, everyone seems to agree these days that the surgery has flatteringly softened her features.

(谢天谢地的是，现在似乎每个人都认为手术后的王妃更加漂亮了)。

youdao

American Mormons, in this sense, seem to have been rather flatteringly typed.

NEWYORKER: I, Nephi

The circles of influence in a flock of birds resemble (perhaps not flatteringly) how our online social networks shape traffic flow to content.

ENGADGET: Editorial: Tech is a flock of starlings

And after returning from Cape Town, I had several offers, with one suitor flatteringly telling me, "we would love to work with the African Journalist of The Year".

CNN: A life-changing experience