Additionally they appear to be modifiable to the extent that they could disappear altogether and the proper solution to this would be to make (as an example) rocket/jet research incremental through 1936-onwards as IRL rather than big jumps in '36, '39, et cetera.
This. Teams did not go from pulling all-nighters to sipping martinis on the beach, they constantly worked at improvements. Do you think Team "Guderian" was completely idle between 1936 and 1939, then proceeded to several months running on coffee and cigarettes to develop Blitzkrieg doctrine?
A gradual year by year increment would make things a lot better, especially for theoretical techs such as rocketry, nuclear physics, doctrines...
Though I see Bomber Harris being a skill 9 team by the end of nearly every ENG game, given how many air doctrines there are...