Will there be a Terratonic datapack update specifically for 1.21.4? I'm not sure if the 1.21 version currently posted on Modrinth is compatible or not.

Good to know! I had tried to upgrade my 1.21.1 world a while ago and ran into issues, but it could've been one of the many other datapacks I use. I'll give it another go soon :).

The 1.21 version should work.