hi Matt, I’m sorry about your experience.
I can have a good guess on one of the problems: TF-DF defines what TensorFlow calls “TF Custom ops”: new algorithms (training/evaluating decision forests)  implemented in c++ to be used in tensorflow.
When one does import tensorflow_decision_forests these “TF Custom Ops” get imported and it’s all fine.
Now when you run !earthengine you are likely starting another (python?) program, and likely it doesn’t import tensorflow_decision_forests, and hence cannot find the custom op  …
Internally we are discussing how to provide a standard way of handling these situations: your SavedModel should somehow inform any other program what libraries (Custom Ops) it should import. But unfortunately this is not automatic yet :\   … it’s in our list of todo’s.
In the short term, this would be easier to solve by modifying earthengine to import the library.