Any examples where the AI copies your formation? I haven't been able to find any kind of evidence to suggest this is the case.
For example in one of my saves i used for a long time, a 4-4-2 Diamond but i didnt see any AI manager use this formation ( change his pref style to 4-4-2 diamond ) in the 10 years i won title after title.
So I think if the AI can indeed copy, it should be heavily buffed to copy it much more often and include more formations that it can copy.