DMESTAN - your set is a Rainbow. The 1927 version did not come with an observation. As for an exact match with respect to car lithography - I wouldn't worry too much about that. I've seen a number of boxed Rainbow sets over the years. Sometimes the litho treatment of the cars in the box match the catalog cut and sometimes they don't.
Catalog cut for 1927
For example - the set below was boxed and the set label was "Rainbow". The car frames were consistent with the 1927 time frame but except for the engine and the fact that one of the passenger cars is blue (wrong window configuration - according to the catalog) and the other does share the window treatment and the color orange with the other car you would have to squint pretty hard to convince yourself that the catalog and the box contents are the match.