Hello Dave,
The grid you're showing in the image is curved, which is something not allowed in Spine. Spine also creates triangles.
I wonder if it could create a grid from a series of points?
I don't think it would be useful anyway, as the grid would have to not go outside of the image bonds, and ultimately it's much quicker to just do the grid in Spine.
You could save an image of the grid as you just did to use as a reference, but please note the points on the star on the left are way too dense and would make your animations very heavy if you started using direct mesh deformation.