Hi!

Well this is no solution, just for comparison:

A while ago I was looking for a method to create terrain entities (chunked), which would match without seam. Here is a screenshot of the transition area:



I had to find / adjust the height manually by zooming in (in wireframe mode).
No matter how exact, there is always a visible seam. Most problematic is a thin white line at the border.
I also noticed the different shading. It is more or less visible, depending on the lighting and the slopes of neighbouring faces. I guess this is because of the influence of connected neighbouring faces and gouraud shading?

This is done with A6 engine btw. and no GameEdit.