Thanks for writing back.
Please note that, not all the objects in the PDF document may have same colorspace (e.g Text can be CMYK, Images can be RGB). However, we have already logged a new feature request as PDFNET-36165, to provide support of converting RGB image to CMYK during PDF generation. As soon as the feature is available, we will let you know.
Furthermore, please note that I have marked this thread as private and now files, shared within this thread, will only be accessible by Aspose Staff. We will really appreciate if you can please share your input/output documents along with the steps of checking colorspace in Adobe Reader. We will test the scenario in our environment and log an investigation ticket, if necessary.