If you apply edits in RAW Power and send the CR2, you will get the CR2 without edits. That’s because there isn’t a way to send edit information between apps (Affinity doesn’t understand Nitro edits and vice versa).
If you send a TIFF (or JPEG, etc.) you will get a rendered image with the edits in Nitro applied.
If you are going to edit in Affinity, then send a TIFF from Nitro and have Affinity replace the TIFF with its own edits.
Image Stacking is not on the roadmap that I put on the website.