Words That Are Very Difficult To Translate

In 2004 a survey of thousands of linguists around the world was carried out to assess what terms, phrases, expressions, etc. were the most difficult to translate.
Why are certain terms so difficult to translate?
Do all words have an equivalent in all other languages?
Or is there a cultural factor that determines our language? Sometimes an existing term in a given culture cannot exist in another, for the simple fact that this concept does not exist culturally in the other.

Here are some of the more complex terms to translate:

Ilunga is the hardest word to translate the world. It belongs to the Tshiluba or  Luba-Kasai language, more than six million speakers in the Democratic Republic of Congo. Ilunga is the ability to forgive the person for an abuse or offense for the first time, to tolerate it a second time, but never a third.

Shlimazl is a term from Yiddish language. It designates a person who is a chronically unlucky.

Radioukacz is a Polish word referring to a person who worked as a telegraph acting for the resistance movements in Soviet Russia.

Naa is a Japanese term that is used only in the Kansai area, to emphasize statements or to agree with someone.

Altahmam is a word in Arabic that designates a specific type of deep sadness.

Gezellig is an adjective in Dutch designating a place I could call warm, homey, pleasant.

Saudade in Portuguese refers to a kind of nostalgia.

Selathirupavar comes from the Tamil language, and designates a certain type of truancy.

Pochemuchka is a Russian word that refers to that person asking many questions.

Klloshar comes from Albanian and describes a man who is a loser.

There are other words in other languages that have no equivalent in any language. For example, for the Eskimos there are many terms that indicate the various shades of white in snow. But for some it’s just white.

Is our job just translation? Or is interpreting another language?

(Spanish version: https://www.trustedtranslations.com/palabras-muy-dificiles-de-traducir-2010-10-20.html)