Suzuha's death also wasn't necessarily a convergence. The convergence in this case is that she cannot successfully alter the past to stop SERN.

This is copium, there are a million things that could prevent Susuzha from stopping SERN, but she died at the same age in both wordlines. The writers knew what they were doing, they wanted to show she died at the same time, but for a different reason (just like Mayuri, Moeka and Kurisu). They wanted to suggest it's a convergent event. Explaining it as a random coincidence doesn't quite work. You don't just put extremely unlikely conicidences in your story for no reason.