Following are a number of back-translations as well as a sample translation for translators of Proverbs 18:21:

• Kupsabiny: “(The) mouth of a person can deliver/save or destroy people.
  So, one should/must guard his mouth.” (Source: Kupsabiny Back Translation)
• Newari: “The word of the mouth
  decides between life and death.
  So they will have to reap the fruit
  of their own words.” (Source: Newari Back Translation)
• Hiligaynon: “What you (sing.) are-saying can-save life or can-kill. Therefore if you (sing.) talk-too-much, [you (sing.)] watch-out for you (sing.) will-harvest the fruit of what you (sing.) are-saying.” (Source: Hiligaynon Back Translation)
• Kankanaey: “Words have-capability to be the cause-of-life or cause-of-death, therefore the one who loves to speak, it is necessary that he accept whatever his words produce (verb form of fruit).” (Source: Kankanaey Back Translation)
• English: “What you say can cause others to be killed or it can cause them to continue to live;
  so those who like to talk a lot must accept the consequences/realize that what they say can cause much harm.” (Source: Translation for Translators)