Following are a number of back-translations as well as a sample translation for translators of Isaiah 38:18:

• Kupsabiny: “The realm of the dead is unable to give you thanks,
  and death cannot praise you.
  Those who have gone to the world of the dead cannot
  trust/hope in you.” (Source: Kupsabiny Back Translation)
• Newari: “place of dead is not able to praise you.
  The dead are not able to praise you.
  Those who go to the grave
  Do not hope in your trustworthiness.” (Source: Newari Back Translation)
• Hiligaynon: “For how can- I -praise you (sing.) if I am already dead? The dead-ones can- no-longer -praise you (sing.) or can-hope of your (sing.) faithfulness.” (Source: Hiligaynon Back Translation)
• English: “Dead people cannot praise you;
  they cannot sing to praise you.
  Those who have descended to their graves
  cannot confidently expect you to faithfully do things for them.” (Source: Translation for Translators)