Can you correct this sentence too?;)

[Ksunya]

Can I say about a tear in such a way? I mean, that it slides down a cheek.

Her tranquility was deceptive. Nobody would have understood it, but for a treacherous tear,that sudenly slided down her cheek.

And after reading this sentence several times, I have such a feeling, that something is wrong

[Coffa]

Can I say about a tear in such a way? I mean, that it slides down a cheek.

Her tranquility was deceptive. Nobody would have understood it, but for a treacherous tear,that sudenly slided down her cheek.

And after reading this sentence several times, I have such a feeling, that something is wrong

"...that suddenly slid down her cheek." - no comma.

Other than that, it's OK. I have a feeling that "Nobody would have understood it..." is probably not natural, but it depends upon the full context.