Once more into the Breach
The L5R prospect sounds like a whole lot of fun, but I have personally had terrible luck with those games getting very far.
Just off the top of my head, if you were to focus on an individual province, where everything is scaled down to a more individual scope, perhaps that would see more success?
For example, court characters tend to dominate in a large palace setting, where as martial characters have nothing to do thanks to a large standing garrison.
Vice versa in an overland campaign.
If there is no lavish court, and there is no huge standing garrison, every character can kind of make it their own. A monk might found a small shrine, a young warrior might try to win the hand of the local Magistrates daughter instead of a Princess, etc.
I do really like the multigenerational aspect. On the off chance the game does last a long time with a quality cast of characters, I think that would be a great cool angle!