Yes, I should rewatch them too as I have not done so for a long time and I do have the commercial releases although I have not had a chance to watch them! They could have better plots because they are mainly reworking of earlier films including two in the Mr. Wong series (Chinese Ring is a reworking of Mr. Wong in Chinatown and Docks of New Orleans is a reworking of Mr. Wong, Detective) while The Feathered Serpent is a reworking of a Three Mesquiteers western called Riders of the Whistling Skull -- although the screenplay writers can be listed as by different people on these films Scott Dunlop was involved in most.
My only contact with the late Ken Hanke who wrote a book on the Chan films was to provide him with a copy of Riders of the Whistling Skull, which I had sought out to see how it compared with The Feathered Serpent -- he had never seen it. Anyway, I am reminded of someone's comment in one of the mystery movies' books of when Toler took over the role from Oland: Toler was not as good an actor so they tried to make up for it by improving the plots and although I am an Oland fan I do like the plots of films such as Treasure Island, Wax Museum and Castle in the Desert which unlike several other Toler entries, are not reworkings of original Earl Derr Biggers novels.
With that...Sky Dragon (1949) Title card to end the real series....