On my first attempt I thought I was dealing with red and green, but during processing it was the yellow slider that made most difference to both the leaf and the raspberries.
I tried again with yellows and blues, and that was more predictable-
I couldn’t do much with the yellows because of the contrast with the writing on top, but by tweaking the blue channel I could almost make the two hues match.
In both photos the original colour photos are visually more pleasing. I wonder if the strong colour contrast is an indication not to bother converting to B&W?