To get correct results, please get the angles before OCR, just after adding the image to the FRDocument and the rotation just after processing. The angle is overwritten after the rotation, so you need to get it before rotation, which happens during processing.
To get the angle, for example, the following lines of code can be used:
double skew = -1;
RotationTypeEnum rot = RT_UnknownRotation;
Where imageDocument is a pointer to IImageDocument.