Pro tip for the flawless gauntlet triumph: Shooting grenades from a grenade launcher through the exit portal thing in the running section counts as runners completing it (I believe one grenade counts as two runners: one for the grenade crossing the line and one for the explosion). If you really want to get those two triumphs done, get to right before the finish line and just spam grenades over the line. If you shoot enough, you’ll get one or both triumphs, regardless of how many guardians actually completed a run.