I didn't see your earlier post.
I had a go at trying to categorise my husband's birthplace; Mackinnon Road in 1951. Wikipedia tells me it's now part of Kwale.county. I assume that you will have a category for each county. If I added a category that would be no problem.
For information: you also mention the official names for the period were "Colony and Protectorate of Kenya, commonly known as British Kenya or British East Africa. "
My husband has three birth certs (Kenyan, South African, British ; his father was protecting all options! ) each has only Kenya.