I mean, if there's a cracked version which is higher than 3.4.02 and lower than v4 technically it might be possible to make it work. At least I might be able to test that version on my end and see if it's okay to work with. It's just that I have no idea which cracked version you guys can even find on the net.
It sucks, yeah, but at least if you have the editor somehow you can edit .json files. Take Live2D for example - games are shipped with a playback function only for animations without an easy way (or nearly impossible) to retrieve the source.
- trial version won't let you change the build for unsupported old JSON file
If they only allow v4 for trial, no wonder it doesn't work. So you really need to find some cracked version from 3.4.02 up to 3.8.99
Saiker1
Which version (number) of spine do you have, is this a cracked one?