Senna's. Small tree's with training. Cassia's of various types. Both have pinnate feathery fronds.I think the yellow blooms bring in and feed Bee's.

Wanting a 12' "tree" usually requires a shrub trained into a standard- Oleander for one.

How about Ray Hartman Ceanothus? Beautiful flowers, low water needs, can be trained into a smallish tree. And if you have good drainage and if that means a coarse, sandy soil, then a ceanothus is just right for that kind of soil. Don't amend it, don't overwater it, don't fertilize it, just let it grow. In five years you should have a sizeable specimen, even if you plant a one gallon. And now is still a good time to plant a CA native, just before the rains start. I think RH can do OK in bright shade.

Arbutus Unedo can take shade and doesn't get too big.

10-12' is a shrub, not a tree. Limb up for tree shape. Toyon Heteromeles arbutifolia or Lemonade Berry Rhus integrifolia would work. Eventually larger than 12', but slow growing and controllable. The berries attract birds, the flowers bees. Keep in mind CA native shrubs tend to be slow growers--it is part of what makes them unthirsty.

I'm in zone 9a, and recently discovered the cascalote tree, Caesalpinia cacalaco, a tree-form relative of desert bird of paradise, native to Mexico. It has lovely lacy foliage and produces panicles of lemon yellow flowers. Here it is semi-deciduous in winter, completely so in hard freeze, but I've seen it flourish in 9b (blistering Phoenix). My multi-trunked knee-high plant reached 15 feet in eight years with a little irrigation, and then I tapered off. Peak height is described as 12-25 feet. We'll see.

As it progressed I trimmed up its lower branches and reduced irrigation. I later planted a taller single-trunked version in a narrow space and it seems to be growing slower than the tiny one I planted.

Good luck with whatever you choose.