Blackcurrant flavors in Kenyas develop in medium roasts and are often absent in lighter roasts. I do not recall the Howell roasts of the Mamuto as having a great deal of them. If you are willing to put in the time, you might do a search for medium roasted Kenya coffee, and email the vendors for details. I did a quick search and couldn't find anything among the usual suspects; so this is likely to turn into a project.
I sympathize, since I'm a big fan of the blackcurrant and clove flavors in Kenya coffees, and unless you roast your own, they are hard to find.