+1 It would be great to have documentation about these things.
These super-powerful functions (Classify and Predict) are really difficult to use in production environments as long as the documentation of procedures employed is so sparse and the procedures themselves are impossible to modify :-(
There are clearly a lot of options for how to preprocess general data. It would be super helpful if these were exposed to the user. At the very least, it would be cool if we could see what assumptions and procedures were done (and have associated high-quality documentation instead of having to reverse-engineer procedures from vague parameter names in <|Associations|>)