Copy Adjustments in Photos does not work with the Extension – that is a Photos-only feature. However, RAW Power automatically saves the last set of adjustments you used on an image as a synthesized “preset”. You can go to the next image you want to edit and use the preset menu to apply those those settings. So, in that way you can get the effect of Copy / Paste.
BTW, it looks that “Copy Adjustments” in the RAW Power app take a few to more than 10 seconds in some cases. When it happens, “Paste Adjustments”s do not appear in right click and they are grayed out in the Edit menu. Is it a known bug?
I don’t know of any such issue. Copy Adjustments comes up immediately for me all the time. Copy Adjustments is only valid if you right click or select an image with adjustments. I’m not sure what could be happening on your machine. Perhaps other things are slow as well?