If there's not an agreement among Websleuths members about the safety of the carseat, it makes me feel that the jury may not unanimously agree that it was unsafe. JMO
Honestly, I'd be flabbergasted if this jury gives a flying fig about RH's alleged violation of a manufacturer's car seat specifications. Even LE, for all their intense focus on the carseat and strange stories about strap settings early on, have never suggested RH was a negligent or a bad father because of the size of Cooper's carseat.
The only possible relevance the car seat has to this trial IMO is whether or not RH would necessarily have seen Cooper in it, even if he had "forgotten " him minutes before.