Post from the game's lead developer — @Tyron.
Here is where Blockbench support stands. The plugin that lets you load, edit, and save Vintage Story shape files is now officially maintained by Anego Studios.
The plugin's code repository is now under the Anego Studios organization on GitHub. It fully supports model editing, texturing, and animation.
The plugin can already save animations with non-linear interpolation. The engine will support that in 1.23.
For now, download the plugin manually from the GitHub releases page. Later it should be possible to install it from Blockbench's official plugin list. A pull request is open to add it to the official Blockbench plugin database and, in the same change, remove an outdated Vintage Story model-format plugin by another author.
Repository: https://github.com/anegostudios/blockbenchplugin
Releases: https://github.com/anegostudios/blockbenchplugin/releases
Pull request: https://github.com/JannisX11/blockbench-plugins/pull/1003