Your right, though. I wouldn't even know where to begin with the necessary precautions to help prevent such things. I can't say I have any games that are on any such markets, but still. What can you do?
It depends a lot about the technology against reverse enginnering.
Actually most native games can get easily cracked. Imagine if the games are free as demo, but there In-App payments to unlock the new episodes, there no reason to crack the In-App payments due to cloud service.
And a JS about detection, if the js is modified, it will disable the engine, but it could make file heavier.
or do not publish the game in China, but it's a bad option.