Following are a number of back-translations as well as a sample translation for translators of Isaiah 9:12:

• Kupsabiny: “The People of Syria shall come from the East.
  and the Philistines shall come from the West.
  All will come to destroy Israel,
  but the anger of God will not subside
  since he still wants to punish those people.” (Source: Kupsabiny Back Translation)
• Newari: “The Arameans from the east and the Philistines from the west,
  having opened [their] mouths, will swallow Israel.
  Still, His anger has not yet subsided,
  and His hand is lifted.” (Source: Newari Back Translation)
• Hiligaynon: “They will-be-destroyed by the Arameanhon in the east and by the Filistinhon in the west, who were like fierce animal who are now ready to devour. But the anger of the LORD still will- not -be-stopped. He is still ready to punish them.” (Source: Hiligaynon Back Translation)
• English: “But, I, Yahweh, say that after I have used Assyria to finish what I want to do to punish the people in Jerusalem , I will punish the king of Assyria because he has been very proud and arrogant/boastful.” (Source: Translation for Translators)