Following are a number of back-translations as well as a sample translation for translators of Proverbs 15:18:

• Kupsabiny: “A sinner stirs up quarrel/strife,
  and/but the one uses the lungs (is patient) cools down quarrel/strife.” (Source: Kupsabiny Back Translation)
• Newari: “Hot-headed people pick quarrels.
  People who have patience
  resolve disputes.” (Source: Newari Back Translation)
• Hiligaynon: “A hot-tempered head starts-up trouble/quarrel, but being-patient stops trouble/quarrel.” (Source: Hiligaynon Back Translation)
• Kankanaey: “The one-who-characteristically-gets-angry, he causes-to-exist quarrels, but one-who-is-patient, he causes-to-exist harmony/reconciliation.” (Source: Kankanaey Back Translation)
• English: “Those who quickly become angry cause arguments/quarreling,
  but those who do not quickly become angry cause people to act peacefully.” (Source: Translation for Translators)