Following are a number of back-translations as well as a sample translation for translators of Isaiah 14:21:

• Kupsabiny: “So, please, kill (plur.) the sons of this king,
  kill (them) for the sins of the forefathers.
  Let (them) not recover until they rule
  and build their cities in the whole land.’” (Source: Kupsabiny Back Translation)
• Newari: “For the sins of their ancestors,
  prepare a place for killing their sons.
  They must not rise to possess the land
  and the land must not be filled with their cities.” (Source: Newari Back Translation)
• Hiligaynon: “‘Prepare now the place where his children will-be-killed because of the sins of their ancestors! They should no-longer invade lands or build-up cities in the whole world.’” (Source: Hiligaynon Back Translation)
• English: “People will say, ‘Slaughter this man’s children
  because of the sins that their ancestors committed!
  Do not allow them to become rulers and conquer all the nations in the world,
  and fill the world with the cities that they rule!’ ’” (Source: Translation for Translators)