Following are a number of back-translations as well as a sample translation for translators of Isaiah 40:4:

• Kupsabiny: “Every hill shall be cut down
  and every valley shall be made smooth/level.
  The ways that are crooked shall be made straight
  and the rough places shall be leveled.” (Source: Kupsabiny Back Translation)
• Newari: “All the valleys will be made high,
  all the mountains and hills will be made level.
  the crooked fields will be made straight
  and fields with valleys will be made level.” (Source: Newari Back Translation)
• Hiligaynon: “Every lower-part will-be-filled-in, and every mountain will-be-leveled, including the rough/uneven places.” (Source: Hiligaynon Back Translation)