I went to the US Copyright website and it looks like I am OK. I posted this query here hoping that if someone does still possess the copyright they will contact me. So far that hasn't happened. The original copyright expired in 1978. It could have been renewed by someone before the end of that year but I have no indication that it was.
I have no record of a BARDEL spelling in my data nor any record of the BARTEL's being in France during that time frame.