en_tn/isa/57/01.md

the people of covenant faithfulness

The abstract noun "faithfulness" can be stated as "faithful." See how you translated "covenant faithfulness" in Isaiah 16:5. Alternate translation: "the people who are faithful to the covenant" or "the people who are faithful" (See: rc://en/ta/man/translate/figs-abstractnouns)

are gathered away ... rest in their beds

Both of these refer to dying. (See: rc://en/ta/man/translate/figs-euphemism)

that the righteous is gathered away from the evil

This can be stated in active form. Alternate translation: "that the righteous people die, and Yahweh takes them away from all that is evil" (See: rc://en/ta/man/translate/figs-activepassive)