The following are some of the languages missing from the list of "Available Languages" in the "Spoken Languages" list in the Movie record screen.

Language: Mooré (also spelled More);
tt0092258 "Yam daabo" in set "Martin Scorsese's World Cinema Project 5" (barcode 715515327213)
https://www.criterion.com/films/35104-yam-daabo
https://en.wikipedia.org/wiki/Moor%C3%A9
Other films in this language: https://www.imdb.com/search/title/?title_type=feature&primary_language=qaf&sort=moviemeter%2Casc&ref_=tt_dt_ln

Language: Yiddish;
tt0030092 "The Dybbuk" in anthology "The Jewish Soul" (barcode 738329251482)
https://kinolorber.com/film/the-jewish-soul-classics-of-yiddish-cinema-the-dybbuk
https://en.wikipedia.org/wiki/Yiddish (NOTE: Yiddish uses the Hebrew alphabet, but is an entirely different language than Hebrew)
Other films in this language: https://www.imdb.com/search/title/?title_type=feature&primary_language=yi&sort=moviemeter%2Casc&ref_=tt_dt_ln

I'll continue to list missing languages under this topic as I encounter them.

Language: Cantonese; (NOTE: This is present in the Title record pull-downs when adding Language to an Audio track, but is missing from the pull-down in Movies. There are MANY THOUSANDS of films in Cantonese, which is a different language than "Chinese/Mandarin".)
tt1941536 "Romancing in Thin Air" (barcode 760137206385). It is the language of virtually every Hong Kong film, as well.
https://www.radiancefilms.co.uk/products/romancing-in-thin-air-le
https://en.wikipedia.org/wiki/Cantonese
https://en.wikipedia.org/wiki/Mandarin_Chinese
https://en.wikipedia.org/wiki/Standard_Chinese
https://www.imdb.com/search/title/?title_type=feature&primary_language=yue&sort=moviemeter%2Casc&ref_=tt_dt_ln