Hello, anyone could giving me idea how to make this loft surface smoother ?

Image 1 : I am trying to use MoI to enhance SketchUp modeling. This case SKP cannot handle surface well and MoI seems to do better job.
but there is some area to improve.

Image 2 : I notice problem are from 2 reference points are too far far each other which may cause not smooth face.

Image 3 : I try to use "Add point: in editor menu but I can't add any new point on this curve and can't improve loft operation

Is there any idea what should try ? I also attached MoI 3D file here.

Thank you very much.