Following are a number of back-translations as well as a sample translation for translators of Jeremiah 17:9:

• Kupsabiny: “The heart of man is a deceiver beyond anything/everything
  and it cannot be healed/treated
  and no person knows/understands it.” (Source: Kupsabiny Back Translation)
• Hiligaynon: “‘The heart of a man is very deceitful and very wicked. No one can-fathom how wicked it is?” (Source: Hiligaynon Back Translation)
• English: “Human minds are extremely corrupt/deceitful,
  and you cannot change that.
  It is also completely impossible for anyone to understand that.” (Source: Translation for Translators)