easiest solution is to flatten the list of inputs that go into the loft component either by the flatten component or with the use of the right click context menu flatten on the input itself.
My preferred method would be to use the path mapper {A;B;C;D} --> (A;B;C} this would keep the option for having multiple objects "flow" through your definition without combining into one messy object.
NB: if the order of curves are not what you wanted swap your A and B inputs on the Merge component to reverse the order or use a reverse List component.