Hey there, the individual triumphs are for completing the missions as part of the Weekly rotation of story missions, on Hero, Legend or Master difficulty only. Despite the 'any difficulty' wording, playing them on Classic or Legendary through the campaign playlist does not count. What is the issue with the Strand aspects? Are you talking about the original ones or the new one? You need to finish the 'Unfinished Business' exotic quest and earn the Exotic Machinegun 'Deterministic Chaos' for the new aspect quest to appear. I can see you don't have this weapon yet, so that should be the next step.