Following are a number of back-translations as well as a sample translation for translators of Proverbs 21:2:

• Kupsabiny: “A person thinks that what he is doing is good,
  but God is the one who knows how the thoughts of a person are.” (Source: Kupsabiny Back Translation)
• Newari: “The people’s thoughts all seem right to them.
  But the Lord tests their hearts.” (Source: Newari Back Translation)
• Hiligaynon: “(It is) possible that we (incl.) are-thinking that everything we (incl.) do is surely right, but only the LORD can-judge what is really our (incl.) motive.” (Source: Hiligaynon Back Translation)
• Kankanaey: “In the viewpoint of people, what they do is totally/all correct, but God knows their purposes/motives.” (Source: Kankanaey Back Translation)
• English: “People always think that what they do is right,
  but Yahweh judges our motives/reasons for doing things.” (Source: Translation for Translators)