en_tn/2ki/23/19.md

Josiah removed ... He did ... He slaughtered ... he burned

It might be best to translate so that the reader understands that other people, perhaps Hilkiah and "the priests under him" (2 Kings 23:4), might have helped Josiah do these things. (See: rc://en/ta/man/translate/figs-explicit)

what had been done

"what he had done"