At her level of responsibility she'd better know. Whatever the case, she's either deceitful or incompetent. Neither answer is flattering or acceptable.
There's always the chance one could have ridden fake-it-till-you-make-it long enough for the engineers to solve the underlying issues...
There are some leaders who are extremely good at convincing you about the importance of belief in a particular thing to the point where you avoid even thinking up those questions - if they are ever cornered (and they rarely allow it to get to that point) they will wriggle endlessly rather than responding to a line of inquiry that bursts the collective bubble.
Do they know? It's hard to argue about their internal motivations.