Problem with Polyline Restoration after Hexagrid Cell Manipulation

Hello guys,

I have a regular hexagrid (white polylines) draped over a semicylinder. My script is meant to fold the grid following the direction described by the black arrow, which is already working!
The entire operation is mainly point based. The original points of the hexagon cells are manipulated (red points) and need to reproduce their original polylines in the end. The regular side length remains the same during the folding process.

As shown in the screenshot, most cells work fine, except the last row! These cells should also retake there fully unfolded hexagonal shape (white overlay). However, they span from on side to the other (red overlay), completely ignoring there prescribed path over the semicylinder. There must be something wrong with my evaluation, but I can't seem to figure it out!

Could somebody please take a look?

Thanks.