Ah, I'm sorry - I misunderstood you! Yes, that scene ends suddenly and unusually, I agree. I'll keep it in mind and take care to change it when I update the demo one last time.
As for the rocks, there is actually a way to cross the river with magic. You can cast Ice beside the sign which suggests there used to be a bridge across the river. Casting Ice in this way produces an ice bridge for the player to cross. My intent with the river was to teach there is rarely one solution, you can make your path forward easier by thinking about it, and the route which plays into Gentiana's talents best (the one that involves magic) is typically easiest.
To counterbalance this, I know there is at least one case where using magic doesn't help. Encouraging players to consider a new and odd mechanic like this without accidentally teaching to assume it's always the solution is a challenge I'm struggling with, and I hope I have succeeded here.