Following are a number of back-translations as well as a sample translation for translators of Isaiah 51:13:

• Kupsabiny: “Oh, have you forgotten the God who created you,
  the one who spread out the sky
  and established the earth here below?
  You live in fear so that you cannot rest any day
  because the man who persecutes you is angry
  and he wants to finish you off.
  But, oh, where is the anger of this person who persecutes you?” (Source: Kupsabiny Back Translation)
• Newari: “Why have [you] forgotten the one who spread out the sky
  and the one who laid the foundations of the earth, the creator of the universe?
  [Why do you go on living,] seeing those who try to destroy you
  and by reason of the anger of those who do evil work,
  why do you go on living, fearing for your own life?
  Where has the anger of the oppressor gone?” (Source: Newari Back Translation)
• Hiligaynon: “Have- you (plur.) -forgotten me who created/made you (plur.)? I am the one-who-spread-out the heavens and placed the foundation of the earth. Why are you (plur.) living in constant fear/terror of anger of the ones-who-oppress you (plur.) and want to destroy you (plur.)? Their anger can- not -harm you (plur.).” (Source: Hiligaynon Back Translation)