Automatic generation of page variants

I've cooked up some customized pages with randomly selected questions from a repo data file. Currently. It works well for human graded questions. And it only works for those kind of questions,

What should I do if I want to create automatic graded pages, for example, a `TextQuestion`, with randomly select questions? I can manage to generate all types of correct answers for all random selected questions in that repo file, just like how I generate the question body. But it seems currently the flow page creation process and grading process are using `page.page_desc` which passed validation, and which is hard coded in the yaml files. One more problem, all my question and answers are generated depending on `page_context` and `page_data.data`, it seems currently validation processes are all done without/before those context are created.

Is it possible to extend the current process without affecting existing pages? Or what can I do to change my pages to fit the currently process. Need your suggestions.