en_tn_condensed/jer/51/53.md

her highest fortresses ... to 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. Alternate translation: "their highest fortresses ... to them" (See: rc://en/ta/man/jit/figs-metonymy and rc://en/ta/man/jit/figs-metaphor)

even if Babylon went up to the heavens or fortified her highest fortresses, destroyers would come

God says this to assure Israel that it does not matter how strong Babylon might be; God will send people to destroy Babylon.

destroyers would come from me to her

This can be expressed with God as the subject. The word "her" refers to Babylon. Alternate translation: "I would send destroyers to her" or "I would send enemies to destroy Babylon"