You already mentioned the reason yourself, I think. As you are using an AOSP ROM it means that you're using a plain vanilla android basis, which - correct me if I'm wrong - obviously doesn't know anything about asus*.* keyboard files. Just copying some files somewhere is not enough to let the system know what to do with it.
You probably have to deal with some scripts, that are run at every start up, that give proper instructions for the operating system. Unfortunately this is way beyond my knowledge.
Save a post - hit Thanks if I helped you!