It’s part of our overseas propaganda efforts to use American linguistic hegemony to void cultural and historical ties with countries we aren’t friends with. The language is Persian, not Farsi.
French in French = Francais
German in German = Deutsch
Spanish in Spanish = Espanola
Dutch in Dutch = Nederlands (old name: Diets, I might add)
Irish in Irish = Gaelic (actually kind-of refers to 2 languages, but ...)
Swedish in Swedish = Svenska
Norwegian in Norwegian = Norsk
Finnish in Finnish = Suomalainen
(Note: most of these have various accents and special characters that aren't correctly typed here, as well as a bunch of nuances that really should be there)
Gaelic is an English word for a family of languages which Gaeilge belongs to.