According to Lt. Lyman's family, Lt. Lyman did survive the exit from the burning B-25 only to be killed in his parachute by the Japanese soldiers on the ground. This was witnessed and reported by a Chinese teen who worked in the hospital where his body was taken. Years later that teen became a Catholic Priest and stayed in touch with Lt. Lyman's parents until their deaths in the late 1950s.
(Much appreciation for information courtesy of C. Lyman and Tony Strotman.)