I don't know too much about the Triangles mold, but from what I understand it was not one of the molds transferred from the USPC Co. to the Burt Co. around 1947. There is no record of Burt having had a Triangle die, hob, or mold cups.
If that is correct, all Triangles mold chips were made before 1947. There are a couple of listings in the ChipGuide with chips dated to the 1950s. Either those dates or attributions are wrong, or the chips were hot stamped many years after they were manufactured.