This movie doesn't have any alternative titles.

Translated titles aren't alternative titles.

Oh it was at /tv: https://api.themoviedb.org/3/tv/71446/alternative_titles But it's still not correct. The site shows me Hungarian title, but the API doesn't give me one.

This TV title has many alternative titles, but no Hungarian.

As already indicated above, translated titles aren't alternative titles.

my api key says its invalid

@caystard said:

my api key says its invalid

The discussion in this topic has nothing to do with the validity of an API key.

@superboy97 said:

This movie doesn't have any alternative titles.

Translated titles aren't alternative titles.

The site shows "A nagy pénzrablás" for me as the Hungarian title and it's the official title, not translated from the English or Spanish name.

@pcroland said:

The site shows "A nagy pénzrablás" for me as the Hungarian title and it's the official title, not translated from the English or Spanish name.

This is the officially translated Hungarian title. It has nothing to do with the alternative title.

@pcroland If you want to get a list of translation, use the /translations method.

What decides whether a translated title end up in the alternative titles or translations?

@pcroland said:

What decides whether a translated title end up in the alternative titles or translations?

The title use for the first release in Hungary is the officially Hungarian translated.

All different titles used later are alternative titles.