That Brace is actually a trailing arm. If you bent that, even ever so slightly, it will cause a bump steer effect. Just like your describing. It throws the rear toe off and can cause a rear wandering at higher speeds. Tires don't cause torque steer either. It's the misalignment of the drivetrain. Check your motor mounts for any play. And glad to hear the new struts came in early and helped out.