en_tn/2ki/15/15.md

the conspiracy that he formed

The abstract noun "conspiracy" can be translated with the verb "plan." It can be stated clearly what this conspiracy was. AT: "how he planned to murder King Zechariah" or "and how he murdered King Zechariah" (See: rc://en/ta/man/translate/figs-explicit)

they are written in the book of the events of the kings of Israel

This can be stated in active form. AT: "you can read about them in the book of the events of the kings of Israel" (See: rc://en/ta/man/translate/figs-activepassive)