Following are a number of back-translations as well as a sample translation for translators of Proverbs 15:13:

• Kupsabiny: “When a person is joyful, then his face shines,
  but if he is sad/angry he frowns.” (Source: Kupsabiny Back Translation)
• Newari: “A joyful heart brings joy to the face,
  but a broken heart makes the spirit weep.” (Source: Newari Back Translation)
• Hiligaynon: “If a man is happy, he smiles, but if he is sad, his face is sad.” (Source: Hiligaynon Back Translation)
• Kankanaey: “It-can-be-seen in the face of a person if he is happy. If he is mourning/sorrowing, he is also extremely discouraged.” (Source: Kankanaey Back Translation)
• English: “When people are happy, they have smiles on their faces;
  but when they are sad, by looking at their faces we can see that they are sad.” (Source: Translation for Translators)