Hello! Adding a checkbox in the Photoshop export script panel to align the origin (0,0) to the center of the canvas during export is a feasible idea. The script can be modified to include this functionality, and it has been suggested that features like this could be added as checkboxes if they become commonly used. You can modify the script to include this feature by adjusting the canvas alignment code, or if you're not comfortable with scripting, you might need to wait for an official update that includes such a feature.

The official feature that includes this does in fact exist:
If you import a PSD using Spine's built in PSD import, it will automatically do this for you.
https://esotericsoftware.com/spine-import-psd/#Origin
Similarly, you can also use the [origin] tag to set it in the middle of a layer of your choice.

As for the PSD script, the origin still has to be set manually every time before export. But hopefully the new PSD import should satisfy your needs!
EsotericSoftware/spine-scriptstree/master/photoshop#origin

saleklar I see! Then you could always import in 4.2, then export a json for 4.1 and reimport in 4.1. But probably altering the script would be faster if you're able to do it!