How to fix shadow acne using render.setShaderAuto()

I’m having trouble getting visually appealing shadows where the output shadow is wavy? I’m running without a GPU and am wondering if that may be the issue. I’m using some code from here to adjust the lighting frustum to the scene.

attached is the code and an image of the problem. Any help is greatly appreciated.

So upon further reading, this is apparently a common problem in computer graphics called shadow acne, and is usually solved by adjusting the bias of the shader. I used the render.setShaderAuto() function in the shadow example Is it possible to change the bias of the auto shader without having to supply my own shader?

So looking at advanced you can do something like this if you supply your own shader.

render.setShaderInput('push', self.pushBias)

However this does nothing if you use setShaderAuto()