Following are a number of back-translations as well as a sample translation for translators of Proverbs 13:20:

• Kupsabiny: “A person who sits with wise people, becomes wise,
  but he who goes around in the company of foolish people suffers.” (Source: Kupsabiny Back Translation)
• Newari: “He who associates with wise people
  becomes wise.
  He who associates with fools
  destroys himself.” (Source: Newari Back Translation)
• Hiligaynon: “If you (sing.) join with the wise, you (sing.) will-become wise also, but if you (sing.) join the fools, you (sing.) will-suffer.” (Source: Hiligaynon Back Translation)
• Kankanaey: “The one-who-companions-with a wise-person, he also becomes-intelligent/wise, but one who accompanies-with a foolish-one, hardship is what he will experience.” (Source: Kankanaey Back Translation)
• English: “Those who habitually associate with wise people become wise;
  those who are close friends of/associate with foolish people will regret it/be ruined.” (Source: Translation for Translators)