The Butter Copley will difficult to repair because the color is so light and unique. I had a similar problem with the handle at the base of my Forest Green Drake Briefbag but it didn't have cracking all the way up the handle, the wear damage was only at the base.
First I used a toothpick to apply small amounts of fabric glue to the damaged area and let it try to try and stabilize it and prevent future damage.
Then I mixed 2 shades of green acrylic paint (forest and olive) with Leather CPR conditioner to get the approximate correct shade and then added tiny amounts of black acrylic paint to get the project shade - as close as possible to the original.
Maybe you could do something similar with buff or camel paints and add white paint to adjust the color?
Then I used a tiny paint brush to apply very small amounts of the mixture to cover the damaged areas and let them dry. I try to avoid using much paint because it is possible the color may change slightly over time.
Finally I conditioned with Leather Therapy and Restorer. Good luck!