Ok so those are typical and rather expected responses in both cases. Neither LH or RH displayed either or any of what you described
Ok I suppose RH did some form of that at the car but many described that as almost acting
No witnesses at the time thought he was acting. One said RH's pain seemed so real to him he actually cried for RH. Another, who testified that she thought he was acting said originally she saw nothing suspicious, that it seemed to her RH was trying to process what had happened, and that it was sinking in, in bits (screaming- quiet).
It's a basic psychological truth that what we believe we see is influenced by visual context.
Spectators and LE saw a man on his phone rather than by the side of his dead baby, laying on the big pavement. The why's of that didn't matter, and for many, still don't.
Even more prejudicial to how RH was viewed by subsequent eyewitnesses was the fact the grieving screaming father was handcuffed and put into a cop car. It's impossible for those cues to have not influenced what people thought they saw. Fwiw.