en_tn/2ch/25/27.md

turned away from following Yahweh

Here "turn away" is an idiom that means he no longer obeyed Yahweh. Alternate translation: "stopped obeying Yahweh" or "started to disobey Yahweh" (See: rc://en/ta/man/translate/figs-idiom)

they began to make a conspiracy ... they sent

The text does not state to whom "they" refers. Retain the generic "they" in your translation if possible.

make a conspiracy against him

The abstract noun "conspiracy" can be stated as an action. Alternate translation: "conspire against him" or "plot against him" (See: rc://en/ta/man/translate/figs-abstractnouns)

Lachish

a city in Judah (See: rc://en/ta/man/translate/translate-names)