Here are a few suggestions:

A white dogwood in full sun in CA is a no-go! Maybe replace with a crape myrtle?

TBH, I find your design too regimented and stiff. A visit to a local independent nursery or garden center could help you to select plants that will thrive in your climate with a minimum of attention. Lobelia would not be one of them,,,,,,,,,,

Duplex - do you live in one half of duplex but own the entire duplex or is entire duplex rental that you own but don’t occupy or?? The answer to those questions should determine how extensive your landscaping plan is or can be.

I would align the trees with your windows. You don't want to block the view or light, so I'd put them between the bigger and smaller window on either side. I would put something else, a clump of birch, perhaps? On the corner. Admittedly, birch is something that looks at home here, far from zone 9. Maybe you want something else.

I have found symmetry in a landscape is hard to keep since plants have a way of deciding how they grow and sometimes in the same yard there are micro climates that mess up the symmetry. I wanted all white flowers in my last yard so diligently removed all the colored plants and replaced with all the white ones looked great the first year the following year low and behold many colors appeared , birds poop and in the poop are seeds for my neighbors colorful gardens. My suggestio n is to purposely not do the symmetrical plan at all this is a duplex do you rent out one side ? If so be a bit flexible in the choices you make If this all rental then easy to care for is the first step

To answer some of the questions, yes, this is a family co-owned duplex. My family member lives in the other side. I plan to live out my days here as it is a nice neighborhood and I've done some nice high end upgrades on the inside. The family member could stay, depending on what happens in the future. It is in a great location, so, for the family member, it would depend on who came into the picture as to staying here or renting it out. The intention is never to sell it, to always keep it in the family.

I am finding symmetry impossible here actually. I did not notice how much bigger my side of the duplex was - I'm on the left. I have more square footage (1207 vs. just under 1100.) I thought it would be a minor adjustment for both of us to have the same size planter boxes. I knew I had more real estate on the left front and I considered putting a stepping stone there. But tonight, late to the game, I realized that the different on the right hand side is a full foot. There is no way to make an identifical size planter on my side work. If I put the tree in the center of the yard, it would be centered withh the window or the planter box

So I am going to embrace the differences because I have to! I just don't know how. Maybe sparcely spaced plantings is a good approach.

I would definitely consider crape myrtle as they don't have huge roots, are not too thirsty and look good all the year round. They also come in different colors so you can select blooms that blend well with your home and surrounding landscape.