It's high quality translation of Chinese Premier's speech.
Obviously you can shrink both. But my guess is you need to keep the Chinese bigger.
I don't know if it's 1:1. I can't read Chinese so I can't give exact legibility numbers. But when I shrink the text closer to the limits of legible English, with letters still basically intact, many of the Chinese characters are completely destroyed (while some are perfectly fine, but with more information per character losing any of them is much worse).
Early computer fonts, for example, couldn’t fit nearly all the strokes and could be read just fine.