Article 1
Kenya is a sovereign Republic.
Article 1A
The Republic of Kenya shall be a multiparty democratic state.
Article 2
The Public Seal of Kenya shall be such device as may be prescribed by or under an Act of Parliament.
Article 2A
(Repeated by 12 of 1991, s. 2).
Article 3
This Constitution is the Constitution of the Republic of Kenya and shall have the force of law throughout Kenya and, subject to section 47, if any other law is inconsistent with this Constitution, this Constitution shall prevail and the other law shall, to the extent of the inconsistency, be void.
You bolded the wrong part. You’re citing a document that was amended in 1999. It’s a mistake to cite a 1999 document and pretend that it indicates a document as it existed in 1963.
The original 1963 constitution of Kenya has been posted many times on this discussion. The word republic does not exist within it.
So then they began to refer to themselves as the Republic of Kenya in December 1963 — Thank You.