Here's a partial list of languages, grouped by families.  It can be
used to determine defaults from one language to another, but I won't
attempt to dictate what those defaults should be at which levels.  It
doesn't cover the Romance languages (I hadn't got down that far,
sorry), but it does include English.

AFRICAN LANGUAGES
  Ewe
  Hausa
  Ibo
  Mende
  Twi
  Yoruba
  HAMITO-SEMITIC
    HAMITIC
      Berber
      Coptic
      Gallinya
      Somali
    SEMITIC
      Amharic
      Tigrinya
  KHOISAN
    Bushman
    Hottentot
  NIGER-CONGO
    BANTU
      Douala
      Ganda
      Kongo
      Ndebele
      Nyanja
      Shona
      Siswati
      Sotho
      Swahili
      Tsonga
      Tswana
      Xhosa
      Zulu
  NILO-SAHARAN
    Dinka
    Lango
    Luo
AMERICAN LANGUAGES
  Aleut
  Apache
  Chinook
    Jargon [pidgin]
  Cree
  Hopi
  Inuktitut
  Iroquoian
  Muskogean
  Navajo
    Trader Navajo [pidgin]
  Nootka
  Ojibwa
  Siouan
  ALGOQUIAN
    Algonquian
  ATHAPASKAN
  DENE
ARTIFICIAL LANGUAGES
  Airspeak [jargon]
  Basic English
  Esperanto
  Newspeak
  Revived Cornish
  Seaspeak [jargon]
  Technospeak [jargon]
  COMPUTER
ASIAN LANGUAGES
  HAMITO-SEMITIC [see African Languages]
  INDO-EUROPEAN [see main heading]
  MALAYO-POLYNESIAN
    Beach La Mar [pidgin]
      Bislama [pidgin]
    Malagasy
    Pijin [pidgin]
    Tok Pisin [pidgin]
    INDONESIAN
      Indonesian
      Malay
        Bazaar Malay [pidgin]
    POLYNESIAN
      Hawaiian
      Maori
      Samoan
      Tongan
  SINO-TIBETAN
    CHINESE
      Cantonese
      Hakka
      Hsiang
      Kan
      Mandarin
      Min
      Wu
    TIBETO-BURMAN
      Burmese
      Garo
      Gurung
      Khasi
      Naga
      Tibetan
  URO-ALTAIC [see European Languages]
AUSTRALIAN LANGUAGES
  Aranda
  Awabakal
  Kamilaroi
  Nyungar
  Western Desert language
    Pitjantjatjara [dialect]
BRITISH LANGUAGES
  Anglo-Danish [extinct]
  Anglo-Latin [extinct]
  Anglo-Saxon [extinct]
  French
  Norman French [extinct]
  Scots
CARIBBEAN LANGUAGES
  Chibcha
  Maya
CREOLE
  DUTCH
    Negerhollands
  ENGLISH
    Aku
    Bajan
    Broken
    Creolese
    Gullah
      Afro-Seminole
    Jamaican English Creole
    Kamtok
    Krio
    Kriol
    Kru English
    Miskito Coast Creole
    Trinbagonian
  FRENCH
    Haitian Creole French
  PORTUGUESE
    Papiamentu
EUROPEAN LANGUAGES
  Basque
FINNO-UGRIC LANGUAGES
  Finnush
  Hungarian
GERMANIC LANGUAGES
  Burgundian [extinct]
  Danish
    Anglo-Danish
  Dutch
    Afrikaans
  Frisian
  English
  German
    Yiddish
  Gothic [extinct]
  Norn [extinct]
  Vandal [extinct]
  SCANDINAVIAN LANGUAGES
    Danish
    Faroese
    Icelandic
    Norwegian
    Swedish
INDIAN LANGUAGES
INDO-EUROPEAN LANGUAGES
  CELTIC
    CONTINENTAL
      Gaulish [extinct]
    INSULAR
      BRITISH
        Breton
        Brythonic [extinct]
        Cornish [extinct]
        Cumbric [extinct]
        Pictish [extinct]
        Welsh
      IRISH
        Irish Gaelic
        Manx Gaelic [extinct]
        Scottish Gaelic
  DRAVIDIAN
    Brahmi
    Brahui
    Kannada
    Kodagu
    Kota
    Kui
    Malayalam
      manipravalam [literay style]
    Tamil
    Toda
    Telugu
  INDO-ARYAN LANGUAGES
    Bhojpuri
    Nepali/Gurkhali
INDO-GERMANIC LANGUAGES
JEWISH LANGUAGES
POLYNESIAN LANGUAGES
ROMANCE LANGUAGES
SCOTTISH LANGUAGES
SLAVONIC LANGUAGES
SOUTH AFRICAN LANGUAGES
URO-ALTAIC LANGUAGES