If you have the address in, for example, Chinese, simply print it off and attach it to the envelope, and write the country of destination in English. There's then no need to write Chinese addresses in alphabetic script. (And BTW, I seriously doubt that the Chinese Post Office has trouble reading
correctly addressed letters written in the Pinyin alphabetic script. It's widely used in China.)
This is an age-old problem, though. The British in India faced it all the time in the Indian Post Office, with the multitude of scripts in use, and some fairly wayward addresses on covers. The British solved the problem by having at least one clerk in all the larger offices who could read the scripts, and write the destination in English on the front. This cover


is a good example. It was posted unstamped (encouraging the post office to deliver it, to recover the postage) and addressed to 'Maharajnagar', as you can see written on the front. The problem with that was that Maharajnagar was an old-fashioned, local name for the town otherwise known as 'Charkhari'. Someone else has finally worked out the mystery, and written it in on the cover as well - after it had travelled over a good part of Central India, looking for a home.