Sorry, I am still a noob. I was going to leave you alone, but since you asked me to let you know if it didn’t work, here is the next screenshot. I think I might have misunderstood you, but you can see the selected option in the spline’s details panel. It is still not working, and there is probably an obvious reason for that. If it is all too much to explain, don’t hesitate to let me know 
EDIT:
It is actually partly working. This is what it looks like in the level.
