Thanks for your kind interest in my search! I have looked on a number of those links you had provided and come up with nothing. It's possible/probable that the surname "Kosin" wasn't always recorded accurately; my own g-grandmother spelled it "Koshion" or "Koshain" all her life! This makes it harder to say with any certainty if a specific Kosin is "my" Kosin.
I have found out that he died in January of 1949 in Nanticoke, and I've sent away for his death record (which hopefully gets to me before the end of the year! Ha, ha!).
All I know for sure is that he was a miner. (Frank was about 60 in 1931, so the 22 year old Frank Kosin you mention cannot have been him, and he was married).
Thanks so much again for your help!