This is some great research.
For those who view the character of Indiana Jones as a linear character circumscribed by an unforgiving strict time line, this is great. There is a lot to be said for this Indiana Jones Paradigm. Many adhere to it, and it gives many fans a strong base with which to view the character.
But I think it is very limiting.
I have a different opinion (hope it won't be too unpopular). I like to view the character of Indiana Jones as limitless.
To me, the character is only limited by his time...the 1930's (and OK, maybe the 40's, 50's and even 60s! But it is all based on the character of the 30's).
To me, there can be overlapping Indiana Jones Adventures; parallel dimensions?.
Indiana Jones can be in Cairo in January 1938, and at the same time be preparing for spring semester at Barnett College. He can be diving into Inca tombs in South America in the Autumn of 1937, and at the same time escaping from a prison in Khartoum, Sudan.
Why limit the most exciting character to emerge from the twentieth century to a circumscribed time-line?
Open your minds to the unlimited universe of Indiana Jones.