Untranslatability is a big claim frequently made.
There are those who insist that a word is untranslatable because they are not sufficiently familiar with the target language.
Then there are those who are too familiar with the target language, the bilinguals, for whom—since they never learnt either language artificially—the two languages exist in parallel. They do not know the route from a concept in the source language to its equivalent in the target because they’ve never had to take it.
Poised exactly in the middle, we expect to find the translator.