Following are a number of back-translations as well as a sample translation for translators of Proverbs 17:21:

• Kupsabiny: “A person with a foolish son is never happy,
  and an arrogant/insolent son does not make his father happy.” (Source: Kupsabiny Back Translation)
• Newari: “For the father of a fool
  there is nothing but sorrow,
  never any delight.” (Source: Newari Back Translation)
• Hiligaynon: “Sadness and painful a parent would fell for his foolish child.” (Source: Hiligaynon Back Translation)
• Kankanaey: “The foolish child, no happiness is what he gives to his father but rather sorrow.” (Source: Kankanaey Back Translation)
• English: “Children who are foolish soon cause their parents to be very sad;
  their parents will not be joyful at all.” (Source: Translation for Translators)