Hi Imme,
The edits are not preserved because of the way that the images are being imported. Apple Photos does not read in RAW Power adjustments.
There are other ways to do this that will preserve your edits.
If you are using macOS Catalina, you can edit images in the Photos library using the RAW Power app (instead of the extension).
To do that:
1) Import your images from the SD card straight into Photos
2) Using the RAW Power app, pick Files > New Photo Library Window
3) Edit the images – the changes will be saved into the photo library and sync over iCloud.
If you are using Mojave, then you have to use the RAW Power Photos extension. In that case, I would do this:
1) Import from SD Card to your local disk (no need to use iCloud here)
2) Select images with RAW Power using ratings or flags, or whatever
3) Import the selected images into Photos
4) Edit with RAW Power Photos extension.
Does that help?
–Nik