I put Boris’ xmp into a different folder and loaded it using “load sidecar file” in lighttable so the original file would not be overwritten. That originally worked, and continues to work for other xmp files I have put into that folder, such as other xmps that I have download from this post.
I did change the name to match the raf and copy it into the same folder as the raf–overwriting the xmp in there, but the raf opens in its raw state and changes the xmp in the folder.
I wonder what would happen if I deleted the database?
You can just rename library.db to library.db.old while darktable is closed.
I have to admit I must be getting senile. I was using the wrong file. Sorry.
I opted to retain the colors while trying to make them more pleasing.
20180922_FUJ8679.raf.xmp (14.2 KB)
Perhaps my inexperience with DT, but RT seems to tame the colors on her spectacles better.
20180922_FUJ8679.jpg.out.pp3 (14.4 KB)Instead of using the Lab curve, you should use the color balance module as it works in RGB mode.
Open the module and select neutralize colors and then fine tune it 
a-20180922_FUJ8679.jpg.out.arp (9.4 KB)
difficult as there seem to be a purple light (reflected for instance on the spectacles) while there is a stong yellow cast from the walls and ground.
