Excellent article, notice all the mentions of "it will probably never be known"? For anyone who has not been to this website, there are a huge collection of great stories and and essays.
I concur -- Joe & Cleoma Falcon -- probably the "first" "Cajun" player(s) to be recognized as such by the "first" recording. Then again, I wasn't around then. Ha! First accordion player in Louisiana was probably Creole -- very likely in New Orleans. I can only discern this historical info through the same videos and books available to everyone else.