Back home I now had the chance to test the method described above.
Technically it works! :-)
(‘Technically’ means that I did not play a complete game to test and find out eventual issues.)
But I found out that you can only define 10 out of 12 technologies.
Paratroopers - called “Airborne_Forces” in the xml
as well as
Improved Mechanized Infantry - called “Improved_Mech_Inf” in the xml
seem to be handled differently. At the moment I have not found out how to define them as “true” right from the beginning.
Anyway… I modified my above post to describe the method more in detail and more understandable, as I hope.