Would there even be a certain means of verifying certification in Kenya, for a colonial era document?
Certainly.
Unless, as I noted MIGHT be done, the relevant page had been torn from the record book.
You see, in the day before computing, the keeper of records in most countries, and certainly in any that happened to be under British administration, kept books, with stamped and sequentially numbered pages, in which were bound the relevant documents. Also they were logged and their data; Book no., pages, etc. noted in the logbook. Separate volumes were kept for deeds, records of birth, marriages, deaths, etc. All the records were kept in ink.
The removal of any page would be noticed because the numbered page would be missing. Also, the missing page could be identified by referral to the logbook.
The system was simple and effective. This and similar paper systems remain in use today all around the world. You can be sure that I Obama really was born in kenya, there was a record of that fact, and one that would be hard to remove from the record without a full scale and extraordinary effort to forge and duplicate several documents to create an alternate record book and log.