So, in [S] Collide, they show the battle against LE as a future vision? And when the kids defeat their opponents nothing of that happens and it becomes what we watched on [S] Act 7 with Vriska?

The fight against LE happens at the same time as the fights of the kids.  Act 7 was finished before Collide which is why it looks like they haven’t been fighting with LE at all at the beginning of A7