Actually, text of the article indicates that this idea belonged to the category of the pipe dreams of the Polish government-in-exile (its contact with a reality was quite tenuous). To start with, the whole idea was generated by the Poles only after both countries had been occupied (the Czechs did not forget that the Poles helped themselves with a piece of the Czech territory). It never got anything but a general agreement to discuss post-war cooperation from Benes, got a lukewarm attitude from the Brits and, what was more important in practical terms, never was endorsed by the SU so that in the early 1943 the Czechs stopped all discussions saying that they would not be interested in any agreement hostile to the Soviet interests.
It could be different if the proposal was made prior to Munich but it was not.
I think it is possible as it solves the Cieszyn dispute which is Ethnically Pole in the first place and likely Poland gets Upper Silesia without the plebiscites.