Seeing as someone has posted a list of countries, I figured in the same vein, I'd add a list of languages that can be used in v4 . Hope its helpful to others.
Afrikaans=Afrikaans
Albanian=Albanian
Amharic=Amharic
Arabic=Arabic
Armenian=Armenian
Aymara=Aymara
Azerbaijani=Azerbaijani
Belarusian=Belarusian
Bengali=Bengali
Berber=Berber
Bislama=Bislama
Bosnian=Bosnian
Bulgarian=Bulgarian
Burmese=Burmese
Catalan=Catalan
Chinese, Mandarin=Chinese, Mandarin
Chichewa=Chichewa
Croatian=Croatian
Czech=Czech
Danish=Danish
Dhivehi=Dhivehi
Dutch=Dutch
Dzongkha=Dzongkha
English=English
Estonian=Estonian
Farsi=Farsi
Fijian=Fijian
Filipino=Filipino
Finnish=Finnish
French=French
Georgian=Georgian
German=German
Greek=Greek
Guaraní=Guaraní
Haitian Creole=Haitian Creole
Hebrew=Hebrew
Hindi=Hindi
Hiri Motu=Hiri Motu
Hungarian=Hungarian
Icelandic=Icelandic
Indonesian=Indonesian
Irish=Irish
Italian=Italian
Japanese=Japanese
Kazakh=Kazakh
Khmer=Khmer
Kinyarwanda=Kinyarwanda
Kirundi=Kirundi
Korean=Korean
Kurdish=Kurdish
Kyrgyz=Kyrgyz
Lao=Lao
Latin=Latin
Latvian=Latvian
Lithuanian=Lithuanian
Luxembourgish=Luxembourgish
Macedonian=Macedonian
Malagasy=Malagasy
Malay=Malay
Maltese=Maltese
Manx Gaelic=Manx Gaelic
Māori=Māori
Moldovan=Moldovan
Mongolian=Mongolian
Montenegrin=Montenegrin
Ndebele=Ndebele
Nepali=Nepali
New Zealand Sign Language=New Zealand Sign Language
Northern Sotho=Northern Sotho
Norwegian=Norwegian
Ossetian=Ossetian
Papiamento=Papiamento
Pashtu=Pashtu
Persian=Persian
Polish=Polish
Portuguese=Portuguese
Quechua=Quechua
Romanian=Romanian
Romansh=Romansh
Russian=Russian
Sango=Sango
Serbian=Serbian
Seychellois Creole=Seychellois Creole
Shona=Shona
Sinhala=Sinhala
Slovak=Slovak
Slovene=Slovene
Somali=Somali
Sotho=Sotho
Spanish=Spanish
Sranan Tongo=Sranan Tongo
Swahili=Swahili
Swati=Swati
Swedish=Swedish
Tagalog=Tagalog
Tamil=Tamil
Tetum=Tetum
Thai=Thai
Tigrinya=Tigrinya
Tok Pisin=Tok Pisin
Tsonga=Tsonga
Tswana=Tswana
Turkish=Turkish
Turkmen=Turkmen
Ukrainian=Ukrainian
Urdu=Urdu
Uzbek=Uzbek
Venda=Venda
Vietnamese=Vietnamese
Xhosa=Xhosa
Yoruba=Yoruba
Zulu=Zulu