The codes and procedures you have posted work as they are intended. However, when I import the comment data file or manually copy a comment from one PDF to the Other (or alternately page to page in the same PDF)
Acrobat DC is still rotating the comment 180 degrees!?
Acrobat is rotating your comments because the source page rotation is different from the target page rotation. You cannot change the page rotation (unless you do some heavy lifting and process each page element at a time, rotate it and then place it in the correct position), so the only way you can fix this is to rotate the comments after you place them - e.g. using the script that Try67 provided.