The Memorial talk likewise changed some years ago though I cannot remember just when. There is no longer any mention of the Passover, the flight from Egypt, Nisan 14 or anything associated with it. They even removed the old Memorial song.. "'Twas NIsan 14 when your glory was seen..."
Personally I think they have realised their calculations have always been wrong so rather than admit it they have just dropped mention of it. A bit like the Creative Days.
I have always thought their interpretation of "between the two evenings" to be nonsense. Cooking a complete sheep in the that short "twilight" period on an open fire would be impossible, my wife cooks a lamb leg for longer in a fan oven!
George