@Mildgyth
Since Starlight still had magic at that point, I think that’s kinda questionable as the culprit, unless it’s because they got there
after the magic was drained.
Aside from Tirek’s living status being potentially questionable if he didn’t win, so Cozy might not have had the opportunity to learn from him (especially if a villain was a factor in his defeat, or Celestia was desperate to stop him and lethal force was the most expedient way), she most likely wouldn’t have the perfect storm to obtain magical artifacts suitable for a ritual she wanted, like she did in S8, where she had infiltrated Twilight’s school, she gained all of their collective trust,
and Twilight (who can be notoriously naive at times, not have her guard up at a
critical moment as shown on multiple occasions) wasn’t being careful enough with securing the artifacts, some of which possibly came from being borrowed from foreign nations, if they weren’t owned by Celestia already.
Twilight Sparkle: Princess Celestia gifted these to our school, since they each represent one of the cultures our students come from.
…Also Cozy might have her younger age/lower maturity a year or two prior holding her back from actually accomplishing her goals, not have her manipulation skills quite honed, or she might’ve even been a blank flank at that point in time.
I don’t think there’s many plausible scenarios where it would’ve been nearly as unproblematic as it was for Cozy in S8, with the varying circumstances. At best, she probably wouldn’t be going to the same school/place as whatever powerful artifacts she wanted, if she even knew where they were, and she’d be liable to attract enough attention to fail trying if she got that far.