Kirk, the symbol in the right most picture on post #1 (the H intersected with a vertical line and a "tree top" on a scabbard) is shown on page 65 of American Military Bayonets of the 20th Century. Under drawings of a bayonet and two different scabbard markings, the author writes, "This M1icon Bayonet and M7 style scabbard are believed to have been made on Formosa for use on their M1 Rifles."

I assume that when foreign countries return their M1 Garands and associated equipment to the US, they just send everything regardless where it was produced. I also assume that the people involved in the sending and receiving don't know (and most don't care) where the items were manufactured. It is up to collectors to solve these mysteries.