Technicolor Movies by Haines:
https://www.amazon.com/Technicolor-M.../dp/0786418095
explains that Technicolor had developed a 35mm monopack in 1939 that was essentially a low contrast version of Kodachrome. Haines says it was developed in concert with Kodak by Technicolor staff member Leonard Troland, and had been available in 16 mm since the 1920s (although he implies it was only used in 35mm size and after 1939). Aerial scenes in the 1941 film "Dive Bomber" were the first to use monopack.
"Glorious Technicolor" by Basten says that the improvement of the monopack was stalled during WWII due to the labs being taken over by the war effort.
Haines says the difference between tripack (star's scenes) and monopack (exterior Africa scenes) is visible in "King Solomon's Mines" (1950).
Haines also says that True Life Adventures were shot on 16mm Kodachrome (implying not the low-contrast stuff).
This all leads me to think that these travelogs were likely shot on the low contrast 35mm monopack. Do you have any of the True Life Adventures to compare to the travelogs?