Unless something has changed very recently, nearly all the instances of architectural models being brought into China need commercial paperwork with customs coding, and in many cases are charged duty. It may make a difference as to whether this model will be re-exported or will remain in China. I assume the latter is the most likely circumstance.

The wood crate container issue is peripheral. Just have a certificate for it attesting to fumigated/treated/etc--those should be pretty standard procedure from whatever company is providing the packing and shipping services for the model.