You did a pretty good job expressing those concepts in English in your post. Sure, there's no single word for each of those expressions, but that only means they're not that popular in everyday usage.

If they were popular enough, we'd say: English does have words for those ideas! They're "feierabend" and "saudade".

Exactly the same as "gesundheit".

Thanks for the compliment, however I feel from the linguistic point of view, I explained them.

Expressing means there is a similar word.

The Turkish "huzun" is a lot like saudade.

You should compare Orhan Pamuk's treatment with Fernando Pessoa.

Thanks for the hint. Although I imagine reading a translated version won't be quite the same thing.

You just expressed these in English.

Although you might spend far more words on it, and it might be hard to properly capture abstract concepts in another language, these are not examples of concepts that cannot be expressed in English.

> You just expressed these in English.

From linguistic point of view, I explained them.

Expressing means there is an English word with the same meaning.

What definition of "to express" are you using? Because expressing does not come with a single word restriction that I know of. I think you mean whether or not there is a translation of a certain word?

We were talking about concepts being "expressable" in any language. Of course many words are not directly translatable (half of Chinese isn't, that isn't news to anybody), so that's not particularly interesting. But you'd be hard pressed to find a concept that is not at least explainable in English.