In light of the issue being that God is demonstrating that he is just, the word "righteousness" (Gr: dike)Romans 3:25, "Whom Yahweh set forth as a sacrifice of atonement by His own blood, through the faith, to declare His righteousness for the remission of sins that are past, through the forbearance of Yahweh;
So Yahweh has given us Yahshua as a Sacrifice to cleanse PAST SINS, as in every thing before we accept Yahshua's blood, (antthing else is adding meaning that is not there), and Yahweh did this through His longsuffering and mercy.
Romans 3:26 "To declare His righteousness at this time, that He might be just, and The Justifier of the one who is of the faith of Yahshua."
is better translated "justice" (Gr: dike).
Then you have missed the writer's contrast between past (OT) and present (NT).See where it says "To declare His righteousness at this time" that is pertaining to this "to declare His righteousness for the remission of sins that are past", that Yahshua is JUST Himself and through His Sacrifice the JUSTIFIER of those who believe in His work.