Following are a number of back-translations as well as a sample translation for translators of Jeremiah 7:31:

• Kupsabiny: “Those people have built altars that are called Topheth there in the valley of the son of Hinnom to as to burn their children there while worshipping. I have never told them even a little to do that, and such a matter has never entered my head!” (Source: Kupsabiny Back Translation)
• Hiligaynon: “They also built a place-of-worship in Tofet, in the Valley/Plain of Ben Hinom, so-that there they will-burn their children at offerings. I never commanded it to them; it did not even enter/cross my mind.” (Source: Hiligaynon Back Translation)
• English: “They have built altars at Topheth in Ben-Hinnom Valley outside Jerusalem,
  and they sacrifice their sons and daughters on those altars.
  I never commanded them to do that;
  I never even thought that anyone would do that.” (Source: Translation for Translators)