As the warnings in your log say, you should re-download Spine from your Spine license page and reinstall. Newer launcher versions are more efficient in various ways and default to 4GB (equivalent to what Spinebot showed) rather than 2GB.
Your skeleton is complex but unlikely to be the problem. Polygon packing can be very intense and may take a long time if you have many images. You can check Fast to get faster packing, though it may not pack as tightly.
