I know very little about the history of US accordions. The assumption that the patent discussed refers to a 'button box' sounds reasonable to me. Piano accordions always had the same note in both directions as far as my research has shown. I do believe that the Stradella bass was not necessarily standard on all early piano accordions, but was adopted fairly early (it apparently originated in the town of Stradella).

I remember seeing in a documentary about WWII (I think it may have been to do with old colour films being available) in which a (german) guy is playing an accordion with a piano keyboard, but what seems like a 'button box' style bass - or else it was a very limited set of about 12 or less bass buttons. The picture was not all that clear, he was not close up, and it was a very short segment of people (possibly including some soldiers) dancing and singing.