en_tn/lev/20/27.md

must certainly be put to death

This can be stated in active form. Alternate translation: "they must certainly put to death" (See: rc://en/ta/man/jit/figs-activepassive)

Their blood is upon them

The word "blood" here is a metonym for the guilt of putting someone to a violent death. See how you translated similar words in Leviticus 19:9. Alternate translation: "the guilt for their violent death is theirs alone" (See: rc://en/ta/man/jit/figs-metonymy)