Following are a number of back-translations as well as a sample translation for translators of Proverbs 28:5:

• Kupsabiny: “A sinner does not know what truth/justice is,
  but people who have committed themselves to God know it well.” (Source: Kupsabiny Back Translation)
• Newari: “As for justice, wicked people do not understand what it is.
  Those who obey the Lord understand it [justice] well.” (Source: Newari Back Translation)
• Hiligaynon: “The wicked people can- not -understand justice, but the ones who take-refuge in the LORD understand it really well.” (Source: Hiligaynon Back Translation)
• Kankanaey: “A sinful-person does not understand justice (loan hustisya; used here to unambiguously refer to justice rather than righteousness; the word normally used would be understood as righteousness in this context), but the one who esteems God, he understands-it properly.” (Source: Kankanaey Back Translation)
• English: “Evil people do not understand what it means to act justly,
  but those who try to obey/worship Yahweh understand that very well.” (Source: Translation for Translators)