Possibly.
A good way to find out would be to find other paperwork from that era and see if it bears the same “Republic” seal at the top.
“The period of post colonial history Kenya began after it attained its independence in 1963 which established it as a republic.”
No need for people to freak out prematurely about fraud. If you were going to make a forgery you would have made the document dates very different.
Yes. Should be an easy check. The authentication process may take awhile.
All somebody has to do is to look at that book and page for documents recorded just before the date of the document and see how the country’s name is listed on other official documents. If there are others indicating “Republic”, then check the book and page referenced in the document as see what’s there.