I have no idea. None of the relevant bits have changed in tk2d 2.3, so I don't think it will be broken. We don't maintain the spine runtime, its maintained by the spine community, I believe.
Spine does not currently support the 4.3 features since we haven't had much time to look into it yet. It will support 4.3 features in the future, hopefully before too long. We need to look into it to be able to give more details.