I'm afraid it's nearly impossible to parse the Spine project file. It's not a file format with a documented structure that is intended to be read by anything except Spine. Even inside Spine we don't have code to parse a specific format, instead the structure can change across Spine versions and is directly related to the data structures Spine keeps in memory.
The only way to do it would be for Spine to do it for you. We could add a CLI option to do so. That wouldn't be a problem if we were currently releasing beta versions, but unfortunately we are in the space between 3.8 non-beta and the 3.9 beta. We are working very hard to get the beta released as soon as possible! I'm very sorry that we aren't able to add the CLI option for you until then.
