I am desperately looking for a proper plugin as well.
If necessary, I would be happy to deal with anybody who would be able to help. I can offer my skills as a CG or traditional animator / cartoonist / illustrator for compensation. Or money if really requested.

Currently, a kind of plugin is already ready : https://github.com/flyover/spine-c2-plugin
But it is not yet quite finished and there are issues.
The two main issues are the following :

• When you create a sprite in your Construct 2 layout while there is already a Spine object in it, something wrong happen on the alpha blending and the parts from the png files are not well cut, there is a black outline around each parts.
• The scrolling feature is not supported by Spine objects. When a camera movement is ongoing, it seems that the Spine object translation will move twice the distance of it, so it gets more and more out of the frame the more you move the camera.