Things have changed and with a greater focus on CRM, cabin crew are instructed to pass on concerns to the Captain be it their own concerns of those of passengers. The exception to that being things that cabin crew know for sure is normal, a good example would be ‘barking dog’ from the PTU on the Airbus for instance.
Regarding the incident at Kegworth, nobody alerted the cabin crew and the cabin crew didn’t raise concerns to the flight crew. Both passengers and cabin crew wondered whether the wrong engine was shut down but neither parties queried it.
Some of the examples given in this thread sound like they happened some years back and the responses could well have been reassurance and maybe messages were passed on to the flight crew. Either way, CRM today is infinitely better.