Following are a number of back-translations as well as a sample translation for translators of Isaiah 56:4:

• Kupsabiny: “This is the word/message that God is saying to the
  castrated (men) who keep the Sabbath.
  those who do what pleases God
  and take good care of his covenant.” (Source: Kupsabiny Back Translation)
• Newari: “For the LORD says like this,
  "To eunuchs who honors my Sabbath day,
  who does work that is pleasing to me,
  and who faithfully keep the covenant
  between me and my people.” (Source: Newari Back Translation)
• Hiligaynon: “For this is what the LORD says: ‘I will-bless the castrated people who obey what I have-(them)-do in the Day For-Resting, and do the things which give- me -joy and obey my covenant.” (Source: Hiligaynon Back Translation)
• English: “They should not say that, because I, Yahweh, say this to the eunuchs
  who obey my laws about the Sabbath,
  and who choose to do the things that please me,
  and who obey all the other laws of the agreement that I made with the Israeli people:” (Source: Translation for Translators)