This can be stated in active form. Alternate translation: "When an enemy defeats your people Israel" (See: [[rc://en/ta/man/translate/figs-activepassive]])
Here "turn back to you" represents submitting again to God. Alternate translation: "if they submit to you again" (See: [[rc://en/ta/man/translate/figs-metaphor]])
The abstract noun "forgiveness" can be translated as a verb. Alternate translation: "ask you to forgive them" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])