Like your avatar, Pathtruder likes to bite (sometimes even its creator...).
Problem you have here is that your second shape file (s2) has line segments that are backwards compared to s1, so each shape section gets twisted while transitioning from s1 to s2. As stated in documentation, "Orientation of segments in shape file is important (a segment should end where the next starts): orientation of generated facets depends of that. MLCad "Swap" button (in line editing window) can help correcting that."...
For the record, path files gets sorted by Pathtruder on input, but shapes files are not, for better flexibility.
Attached the corrected s2 file, and result obtained from your command line (using -ts 10 instead of -ts 1 to get a smoother shape transition). Note that it would be probably simpler to generate only one quarter of the shape and use mirroring (assuming shaper is really symmetrical, I have not verified). Maybe resulting mesh resolution is a bit too high?
Problem you have here is that your second shape file (s2) has line segments that are backwards compared to s1, so each shape section gets twisted while transitioning from s1 to s2. As stated in documentation, "Orientation of segments in shape file is important (a segment should end where the next starts): orientation of generated facets depends of that. MLCad "Swap" button (in line editing window) can help correcting that."...
For the record, path files gets sorted by Pathtruder on input, but shapes files are not, for better flexibility.
Attached the corrected s2 file, and result obtained from your command line (using -ts 10 instead of -ts 1 to get a smoother shape transition). Note that it would be probably simpler to generate only one quarter of the shape and use mirroring (assuming shaper is really symmetrical, I have not verified). Maybe resulting mesh resolution is a bit too high?