You can click on the track to make it switch.
But I agree that it is not intuitive, but I didn't find a way to make it obvious that this functionality exists.
Trijam #333 Part 2/3: The 3 hour game jam » Entries » Balthazar Glimmerail : Magic jewels delivery system
Viewing post in Balthazar Glimmerail : Magic jewels delivery system jam comments
Hahaha somehow in all my clicking around I never discovered this!
Well, I was playing on hard mode I guess :)
It might be something fun to play with for later levels, to limit that function. And I wonder if there's any interesting puzzles to be found with a magic crystal that switches the track direction after it crosses over?