Oh, sorry, I guess what I mean is that when you export a 4.0 version json file with the spine 4.1.26 you cannot run it with the 4.0 unity runtime.
I realize I was a bit oblivious with my question. Actually my question is, is there an estimate for when a stable 4.1 or higher version will be available, both for spine and Unity run time? But now this might not be the right forum section to ask this.