Authenticity will depend on BK & PG. If this can be traced back to the BK & PG, then that’s all that is needed. Is BK & PG public record in Kenya? Is here.
Any title search company in the U.S. can request a copy of the BK & PG from the recorder’s office in Kenya. May cost a few dollars. Usually so much for the first page and so much for each page thereafter. Has anyone done that?