Can't figure out what I'm doing wrong

[Graeme Dice]

Sencha said:
I was probably about halfway through the 2nd game year, controlled around seven provinces and my average army was around twenty units.

You have hardly any provinces for this late in the game. You want to be capturing a minimum of at least one province a turn for the first ten turns, and hopefully to have 15-20 provinces by turn 10.

I had three dedicated researchers (the Pretender, and two expensive research units).

By turn 20 you should have at least 20 researchers, especially with the cheap mages that Jomon has. Your pretender should also probably be out conquering provinces by himself, not rsearching in your capital where he can't affect your game much.

I'm not draining my funds every turn, I'm taking over every province I can, and I'm imposing higher taxes on the provinces that are worth it.

Never set the tax rate higher than 100% unless you need gold income immediately. It causes unrest and kills population.

For Late Era Jomon, your pretender should have order 3 and production 3. You should probably also pick misfortune 2 or 3. You'll also want a base dominion of 6. Once you make these standard starting choices, you can play around with the rest of the settings.