Following are a number of back-translations as well as a sample translation for translators of Isaiah 64:4:

• Kupsabiny: “There is no one who has heard about another God
  from the ancient generations.
  And there is no one who has seen another God
  who is doing things for the people who trust in him.” (Source: Kupsabiny Back Translation)
• Newari: “God beside you who work wait for on
  For since the world began,
  never any ear has heard
  and never eye has seen.” (Source: Newari Back Translation)
• Hiligaynon: “From the ancient-times until now no one ever has-heard or seen a God who is like you (sing.) who helps the ones-who-rely on him.” (Source: Hiligaynon Back Translation)