I’ve been playing MSB on my PS5 in the UE 4.26 version. Overall, the route is excellent and still one of my favourites. I’ve noticed a few issues though: The sound of freight train consists doesn’t work properly. The front of the train has sound, the rear of the train has sound but there is no sound in the middle of the train. Sleeper load in is still very noticeable, but I don’t know if this has even been touched on this route yet.
Sleeper load-in hasn't been addressed on any route. It's a core issue, to which no solution has yet been found.