Don't jump to conclusions too quickly :)
It's maybe not very clear (and it obviously lacks the documentation needed) but you can access uniforms on a spriteRenderer or a modelRenderer in code: `this.actor.spriteRenderer.getUniforms();`. This API is about to change but as v0.18.1, as soon as you modify the value you get, it will be applied to the shader.
In the next version, it will be `this.actor.spriteRenderer.uniforms.getFloat(nameofuniform);` or `this.actor.spriteRenderer.uniforms.setFloat(nameofuniform, value);` to match better the overall API in Superpowers.
Hopefully, that helps you!