I believe these are confirmed. NWS would send a survey crew to potential sites of tornadoes the next day to identify if a tornado did touch down and determine the path, severity, etc. With that said, a tornado from the 1950's may had gone unnoticed/uncounted if it happened in an open field with nobody around to see it. Radar would help the NWS office know if a storm had rotation and where the rotation was located to investigate potential tornado sitesGated article, but confirmed, or radar indicated? Let's not pretend that 30, 40 or 50 years ago (or longer) they had the same level of ability to accurately count these things beyond looking at the damage.