I wouldn't make too big an issue merely about Obama Sr.'s age being two years off on his BC. A father's age on a BC would be obtained simply by asking the mother if the father isn't present at the time of the child's birth. In this case, the mother might not have remembered correctly or remembered an incorrect age that Obama Sr. could easily have told her. That's assuming, of course, that this BC was bona fide and made shortly after Obama II's birth in Hawaii.
It's the father's race, designated as "African," that's much more problematic in analyzing the BC's authenticity or lack thereof. As pointed out previously, the usual bureaucratic racial designation in 1961 pertaining to Obama Sr. would be "Negro" or "colored."
If she not only knew his middle name and the exact spelling of his complete name, as well as carrying his child for nine months, she also knew his age and plenty of other details about him!