Here’s a version of FrostFeast 2016 that should be compatible with Alpha 23 Unstable (release 771). This is a compatibility-only update, so no new features (well, except FF items have appeal). There might still be bugs, but I was able to go through the main quest without any issues.
https://drive.google.com/file/d/1-bLIllB-PLr-44Jiih9f0mnhX0B7TUzq/view?usp=sharing