en_tn/jer/51/57.md

her princes, her sages, her officials, and her soldiers ... her high gates ... her aid ... for her

The people of Babylon are spoken of as if they were the city itself, and the city is spoken of as if it were a woman. AT: "their princes, their sages, their officials, and their soldiers ... their high gates ... their aid ... for them" (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-metaphor)

they will sleep in an unending sleep and never wake up

They will be dead. See how you translated this in Jeremiah 51:39. (See: rc://en/ta/man/translate/figs-euphemism)