This is a continuation of the following trophy:
The main bit behind Tyria's Cosmosphere levels is that, from Level 2 and Level 3, it is basically repeating the same few events over and over again to try and make some change to them. This is especially true in Level 3, where it deviates into three alternate endings (which can be obtained regardless of if you're on a true ending path for Saki or Finnel and have accepted their confessions already).
For event details helping you complete the levels, follow the 100% CS solution below: