It was a process that director Niki Caro said was ongoing and frequent, and she revealed to Film School Rejects that several experts in Chinese History and other fields were even consulted for Mulan, which draws inspiration from the legendary heroine of that name more than the Disney animated classic. When asked specifically if their input changed parts of the production along the way, Caro confirmed that was something that happened quite a bit.
Article source: https://www.cinemablend.com/news/2554134/all-the-work-that-went-into-mulan-to-make-sure-the-movie-was-authentic-to-chinese-culture