Following are a number of back-translations as well as a sample translation for translators of Isaiah 29:21:

• Kupsabiny: “God shall put an end to those people who falsely accuse others,
  those who protect/shield the people who have made mistakes
  and do not do justice to people who are righteous.” (Source: Kupsabiny Back Translation)
• Newari: “Any person who is giving blame to people by talking,
  and in court, catches the other party in a trap,
  and when making judgment on one who has no guilt,
  by giving false witness causes false verdict [lit. far from justice].” (Source: Newari Back Translation)
• Hiligaynon: “including all who accuses which is not true, the ones who scheme so-that the judges be-convinced, and the witnesses who lie so-that the innocents will- not -be-given justice.” (Source: Hiligaynon Back Translation)
• English: “Those who testify falsely in order to persuade judges to punish innocent people will vanish/disappear.
  Similar things will happen to those who by lying in court persuade judges to make unjust decisions.” (Source: Translation for Translators)