When you import an alignment from Land Desktop it is not very easy to edit it. In fact, it seems that you loose most of the Horizontal alignment editing functionality of Civ3D.
Land Desktop knows where PI's are for horizontal alignments. It would be nice if Civ3D would allow you to import the curve PI's of the alignment instead of just the curves.
As it is now, grip editing an imported curve changes the curve radius, but the endpoints stay the same. So, if you edit the curve, then the tangents are no longer tangent to the curve. It would be nice to have the option to import an alignment as if it was created with the tan-tan layout tool with curves added later. Then, adjusting the curve would adjust the PC and PT accordingly. You would also be able to grip edit the curve PI as well.