If you didn't changed graphics adding new sprites, you don't even need to generate .atlas file and a new .png file(s).
Bone only edits are in .json file.
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Unpack it anywhere you want. Launch it. File-Open and select an .asset file in game data folder. For Minotaur only edit and to get the idea how to work with it you need to open sharedassets21.assets file only.
You'll get an 'Assets Info' window. JSON and Atlas files in these archives are 'TextAsset' type, so you can either Filter it, using View-Filter or just find it by sorting it. Search for a minotaur file, it's called s_minotaurosu_ero_spine in this archive, take a note it doesn't seem to have .json extension.
Once you found it, select this file and press 'Plugins - Import.txt'. Now you need to add .txt extension to your .json file, so it would look like this s_minotaurosu_ero_spine.json.txt (I attached my edited .json file for this scene, so you'll have an example).
This will allow UABEA to see it. Once the file is replaced, press File - Save and then File - Save as... and this will generate a new .assets file. Save it in any other folder, not in game data. Always make backups for original files and assets. Now, replace put a new generated asset file to Data folder.
Now, depending on your Spine export options there might be issues. I'm using 3.4.02 as a base version, later version might have different options and layouts, but here's options:
According to my experience it should produce a compatible .json file you can use for the game. I also remember that there's a certain spine version limit, like 3.4.02 and up to 3.6.xx are supported, later versions might produce a non-compatible output. Don't remember this one well, sorry folks.
As for new .atlas and png generated with spine, it's a bit tricky and I'm not yet sure how to set it up perfectly, need more testing.
unkeptdragon01
I think I know what you mean, but the problem with all that is it will require a good amount of work: redrawing sprite assets, adjusting everything in spine and so on.
I'd say we need to get more people to be able to learn how to use spine properly and to be able to generate a valid .json, .atlas .png exports. And then to import it properly back to the game. That's also a lot of effort, but seems manageable to me.