Following are a number of back-translations as well as a sample translation for translators of Jeremiah 31:21:

• Kupsabiny: “Place (sing.) signs at the side of the road
  so that when you (plur.) come back (they) will show you the way.
  Fix/stick (sing.) that road in the head
  the road that you travel on.
  Oh, Israel, my beloved, please return,
  come back here to your cities.” (Source: Kupsabiny Back Translation)
• Hiligaynon: “‘Set up signs and guideposts on the road. Mark well the path by which you pass-through for this is the path by which you will-pass-through when you come back. O those from-Israel, return now to your towns.” (Source: Hiligaynon Back Translation)
• English: “You Israeli people, set up road signs;
  put up posts along the roads
  to mark the road on which you walked when you were taken from Jerusalem.
  My precious/beloved Israeli people,
  come back to your towns here.” (Source: Translation for Translators)