en_tn/rom/15/04.md

For whatever was previously written was written for our instruction

You can translate this in an active form. Alternate translation: "For in times past, the prophets wrote everything in the Scriptures to teach us" (See: rc://en/ta/man/translate/figs-activepassive)

our ... we

Paul includes his readers and other believers. (See: rc://en/ta/man/translate/figs-inclusive)

in order that through patience and through encouragement of the scriptures we would have certain hope

Here "have confidence" means that the believers will know that God will fulfill his promises. You can make explicit the full meaning in your translation. Alternate translation: "In this way the scriptures will encourage us to expect that God will do for us everything that he has promised" (See: rc://en/ta/man/translate/figs-explicit)