Following are a number of back-translations as well as a sample translation for translators of Jeremiah 15:12:

• Kupsabiny: “But can a man break iron,
  the iron that comes from the North, or maybe bronze?’” (Source: Kupsabiny Back Translation)
• Hiligaynon: “‘As/Since no one can-break the bar of iron or bronze, no one can- also -defeat the enemies from the north.” (Source: Hiligaynon Back Translation)
• English: “Yahweh also told me to say to the people of Judah,
  ‘our enemies, who are as strong as iron or bronze, will attack you from the north;
  no one will be able to stop them.” (Source: Translation for Translators)