Not Russian, but 35 years ago there was a widely repeated translation joke: The slogan "come alive with the Pepsi generation" was translated into Chinese, but it literally meant "Pepsi revives your dead ancestors."
That example may be apocryphal, but translations are interesting. It's something to be mindful of when talking with otherwise fluent ESL people.
I had a very intelligent and fluent coworker who knew the English phrase "to shag" from the Austin Powers movies. She completely misinterpreted the meaning of "a shag carpet," though. It was so funny (and came up so infrequently) that no one ever corrected her.
I know that in general, proverbs are difficult to translate because they assume a lot of cultural knowledge to convey their idea.
Like if I say to you "bird in the hand", you'll understand that I'm referencing the notion that there's value to a sure thing that can outweigh the value of potentially having more.
If you ever watch a UN speech, the translators sometimes pause for a bit to figure out how to convey not just the literal words, but also the meaning and the meaning in context.
onion sorrow
the horse did not roll
There are elderberries in the kitchen garden, and your uncle in Kiev
There's a pretty good Nicole Kidman thriller called 'The Interpreter.' Kidman plays a UN translator. There's a cute little throwaway scene where some of her colleagues are chatting. One says the the American used the phrase 'pie in the sky' and she had to change it to 'castles in Spain.'
In last season of "The Boy" one of the characters used a russian proverb "Trust but verify" and I learned that it was popularized in USA by Ronald Reagan.
I didn't say "untranslatable". Please don't put words in my mouth.
Though there are sayings that are virtually untranslatable between cultures because their conceptions of the world are so different.
It's often very difficult to translate sayings across cultures, because there's no one-to-one mapping of words, let alone ideas/concepts.
Take a look even at the difference between French and English, where how you count isn't even close to the same. Then read some Moliere and Shakespeare, seeing how their wordplay is different because of language differences. And these are two countries with a long relationship, with French spoken by the upper classes in Shakespeare's time.
I have several books of sayings/proverbs collections, and it's fascinating to read things translated by people with extensive understanding and knowledge. Even then, sometimes the best translations are just incomprehensible to me, since I grew up in a culture that's vastly different from the origin.
Very old sayings are especially interesting (e.g. Things written in something like Sanskrit). It can be so difficult to connect to a culture that hasn't existed in so long (or has an existing great-great-great grandchild that's quite different).
Again, even from US English to British English can be surprisingly opaque, sharing a common language but unique environs.
Take for example sayings like "my cross to bear" and "good Samaritan". Those are both from the bible, but they're oblique references to saying that require a LOT of explanation themselves, but they're so ingrained you can just reference the full saying to get the message across.
If I were to say, reference "one thing which never dies", pretty much everyone would be guessing at the meaning. Basically nobody knows it's a reference to a saying about the reputation people leave behind after death, based on the Norse Edda's.
The lesson seems to be that how people know you is the most important thing in life, beyond family and your life. And that explanation doesn't cover it, because none of us have the correct cultural background to interpret it. (If you happen to be a scholar, I'll happily be corrected).