Yeah, that very article you posted the link to. The one where they list 8 defects in the document. The one where they say their sources call it a forgery. The one where they posted an actual picture of an actual Kenyan birth certificate from that period and which didn't look anything like Smith's document. That article.
Yes, but that is because they were looking at one form of BC, while Smith's document purports to be another. The official government "Return of birth" was more akin to our short form, or just a birth ledger, while the Smith Document is more akin to our older hospital birth certificates, with the footprint.
And you'll notice that they are careful not to call Smith's a forgery, just that "their sources" say it is. All it would take would be one certificate that looks like Smith's to blow their argument right out of the water.