China only does assembly. They do not design the chips, and they do not write the software.
Not only that, there is the problem that nearly everyone chooses to ignore, the insecure baseband system and processor. One of the biggest moves China could make would be to both design and certify a processor and a baseboand OS. Then they could just run their own version of Replicant or whatever on the other processor while knowing that the 'hidden' part of the system is also clean. It's the certification that is a big barrier for most teams but China could squash it easily.
"natural langauges" are too imprecise. Even native speakers often get confused talking to each other. It's just that most people don't notice the back and forth with clarifying questions since it comes "naturally". It seems that for any high level of natural language processing a fully sentient AI would be needed for the interpreter.
An interesting experiment might be to use ithkuil for the UI at first to reduce ambiguity and imprecision. That might make it easier to gauge how much AI would ultimately be needed.
I tell them to turn to the study of mathematics, for it is only there that they might escape the lusts of the flesh. -- Thomas Mann, "The Magic Mountain"