tl;dr: Lithuanian language in the TMDB is listed with a weird unicode control character and should actually be "lietuviškai"

Long version

An example of a film in the DB with a Lithuanian translation (though for all examples I pulled with a LT translation, this was the same):

# Ex Machina
curl 'https://api.themoviedb.org/3/movie/264660/translations?api_key=<apikey>'

Returns this object for Lithuanian

{
"iso_3166_1": "LT",
"iso_639_1": "lt",
"name": "Lietuvi<9a>kai",
"english_name": "Lithuanian",
"data": {
"title": "Ex Machina",
"overview": "Jaunas kompiuterių genijus, programuotojas Kalebas dirba vienoje didžiausių interneto kompanijų pasaulyje. Kartą vaikinas laimi konkursą, kurio pagrindinis prizas – galimybė savaitę praleisti su kompanijos įkūrėju ir vadovu Neitanu.  Neitano namai kalnuose, toli nuo žmonių, kartu yra ir jo mokslinių eksperimentų vieta. Degantis smalsumu Kalebas jau pirmąją dieną sužino, kad Neitanas dirba prie unikalaus projekto: dirbtinio intelekto roboto. Vaikinas dar labiau apstulbsta, kuomet pamato patį robotą: nuostabaus grožio merginą, vardu Eiva",
"homepage": ""
}

Notice the odd unicode character in the "name" field.

I don't know much about Lithuanian, but it seems to me TMDB has the character U+009A (the "single character introducer" control character) in that field when it meant to have the character U+0161 (š, "latin small letter s with caron").

But also I think that might even be the wrong word entirely. In the ISO 639-1 standard for language codes Lithuanian is listed as "lietuvių kalba", which is close to what the TMDB front-end is reporting so I dunno ¯_(ツ)_/¯