Gosh, the Canadair Argus. My last sighting of this somewhat strange hybrid aircraft (airframe similar to Britannia 312 with Wright R3350 turbo-compounds) was at St.Ives, Cornwall in September 1972. Walking around the town I was surprised to hear the unmistakeable muffled roar of the big Wright's at climb power, then over the rooftops flew the Argus, on departure from St.Mawgan, no higher than around 1500ft in a very shallow climb.
Re the B29, although these were equipped with supercharged Wrights, they weren't the turbo-compounds as fitted to Super Connies and DC7's. As far as I'm aware, these weren't introduced until the early 1950's, initially on the Lockheed Neptune. Even the early Super Connies had non-compounded Wrights (the basic L1049).
Yes, the Wright turbos were renowed for their unreliability, usually involving failure of the PRT itself (power recovery turbine). So why did Canadair choose this powerplant for the Argus, with its role of extended overwater reconaissance? I remember reading an account by a retired TWA skipper failures were dramatically reduced if the supercharger was not "changed gear" to its second stage at higher altitude. So maybe this procedure was adopted by crews in preference to a higher cruise altitude with the chance of a PRT failure.