I think the scale parameter should just be adjusting the spine rendered texture, not the rendered quad size in the C3 canvas (which it seems to be doing.)
I'll take a look at it.
Overall, what scale is used for is to reduce the rendered image size so that it fits in the texture. So, in this case, I do expect that you will need to use a smaller scale (like 0.3), but you can then scale the size up of the Spine object to make it larger when displayed.