Following are a number of back-translations as well as a sample translation for translators of Joel 2:13:

• Kupsabiny: “Do not just/only tear your clothes
  but change your hearts.’
  Return to God because his stomach is white (kind, generous, merciful) and he cries with (has mercy with) people. He does not quickly become angry and he has great love. He turns his thoughts and does not punish those who repent.” (Source: Kupsabiny Back Translation)
• Newari: “Tear your heart and
  not your clothing in your grief.
  Return to the LORD your God
  because he shows compassion and is gracious,
  He is slow to get angry.
  and he shows everlasting dayamaya,
  He is always ready to withhold his punishment.” (Source: Newari Back Translation)
• Hiligaynon: “You (plur.) repent wholeheartedly and do- not just -show-off in repenting by tearing your (plur.) clothes. You (plur.) return to the LORD your (plur.) God, for he (is) merciful/compassionate and shows-concern. He (is) loving and not quick to-get-angry. He (is) ready to change his mind/thinking not to send destruction anymore.” (Source: Hiligaynon Back Translation)
• Kankanaey: “It-is-necessary that you be persistent/resolute in repenting, because your tearing your clothes does not suffice to show your repentance. Return to Yahweh your God, because he is patient and consistently-merciful/kind. He does not easily get-angry but rather he is consistently-loving. He is prepared to forgive and he does not continue to punish.” (Source: Kankanaey Back Translation)
• English: “Do not tear your clothes
  to show that you are sorry;
  instead, show that you are sorry.’
  Yahweh is merciful and kind;
  he does not quickly become angry;
  he faithfully loves people.
  He does not quickly become angry;
  instead, he greatly and faithfully loves you,
  and he does not like to punish you.” (Source: Translation for Translators)