Following are a number of back-translations as well as a sample translation for translators of Isaiah 48:18:

• Kupsabiny: “If you had followed my laws
  you would have received a blessing that flows like a river,
  and you would have been victorious like a storm of the ocean.” (Source: Kupsabiny Back Translation)
• Newari: “If only you had obeyed my commands carefully,
  your peace would come to you like a river
  and your righteousness will come like the waves of the sea.” (Source: Newari Back Translation)
• Hiligaynon: “If only you (plur.) had-obeyed my commands, the goodness would have-flowed to you (plur.) like a river, and your (plur.) victories would have been successive/followed-one-after-the-other like the waves which splash on the side.” (Source: Hiligaynon Back Translation)