Hi !
The curves you have created are too heavy, meaning there are too many segments. Do you have an untouched model? With no rounding done on it?
I too believe you are asking the plugin a bit too much, especially with so many segments.Not really the plugin, but when you give Sketchup that much to chew, things might get unstable. You could try to divide the surfaces where there are straight lines and run the plugin twice or more for each surface.