Just guessing the other two would probably have been 1970ish - also seem a little late for B&W photos, especially since basically all of the Barry’s 1960’s Hawaii photos I can think of were in color.
Just a suggestion; Photo processing was a big deal back in the 1960s, and even into the 1970s here in America. The Black and White process was easier, if I understand correctly, and the color photo process was more difficult. Perhaps Indonesian photo processing labs were not well suited to it, or perhaps the cost was prohibitively more. Possibly they also had a camera that wouldn't accept anything but black and white film. Dunno. Just some stuff to keep in mind.
I just did a quick glance through family photos from 1960 -1972. Almost all were color, but in the early 1960’s, I would say 5% were B&W, with only sporadic B&W photos in the late 1960’s with the last B&W photo about 1970.
If my sample was used (without considering the Indonesia factor you mention) then I think the three photos being B&W would be unusual and the fact that they look phony.
If it is found that most photos in Indonesia around 1970 were B&W due to the factors you mention, then I believe that would eliminate the B&W question - just leaving the phoniness question.
