I actually like the long games just because they give more time to research. There is always a mid-phase in the game where you can have a period of calm if you play your diplomacy well - I use that to build and tech up.
I can see the issue of not getting enough techs in a short game, but the game is not called "short" without a reason.

I would not really mind if the research bonuses would be a bit higher for some of the buildings, as it seems like +150% is not really all that much (that is about as much as I would have in mid-game with one academy).

Perhaps a certain kind of boon could apply to techs after most other clans have researched it. For instance, if 3/4 daimyos have a certain tech, the research time would drop by a turn or two.