There are a few issues with the decompiler that makes it incomplete:
Missing $bolton and $prefab QC attachments (can provide you with a header with structs if needed, there are also supposedly other unknown QC attachments or even original attachments that had their syntax changed)
Attempting to decompile the Player's model and recompiling it will throw an error (too many animations, duplicated attachments)
Some models lose their eyes (such as Player's model)
There are a few issues with the decompiler that makes it incomplete: