Following are a number of back-translations as well as a sample translation for translators of Proverbs 17:20:

• Kupsabiny: “A person whose thoughts have gone astray (in a bad way) is in a bad position
  and a lying person falls into suffering/trouble.” (Source: Kupsabiny Back Translation)
• Newari: “People who have evil thoughts
  and who lie will never prosper.
  They will be destroyed.” (Source: Newari Back Translation)
• Hiligaynon: “A man whose thinking is crooked will- never -succeed, and a liar man can-obtain destruction.” (Source: Hiligaynon Back Translation)
• Kankanaey: “There-is-no benefit that is gained by a person who thinks and speaks evil. Only/All hardship is what will arrive to him.” (Source: Kankanaey Back Translation)
• English: “Those who have perverse minds/are always thinking about doing evil things will not prosper,
  and disasters will happen to those who always tell lies.” (Source: Translation for Translators)