Certainly it was known by many of the key engineers, possibly some in management, but the interesting question is did Musk himself know?
It's hard to believe he would knowingly tarnish the brand by delivering the least reliable SUV in America to customers.
On the other hand, it was already 18 months late - the pressure from all sides to deliver must have been enormous, with people on the edge of burnout.
As a purist, it's easy to say hold out as long as needed and don't compromise, but at some point it could have become a duke nukem forever scenario.
Pick your poison.