Flex language support

We just hooked up our new Flex box and most things seem to work correctly.  However, my wife likes to watch some Youtube videos and channels of Chinese origin, and the Chinese fonts are not showing up in the Youtube listings.  We just see empty boxes instead of Chinese characters.  Previously, we were using an old Android TV box that didn't have this problem.  Is there a way of downloading additional fonts to the Flex box, or some other workaround?  Since many customers are of an international origin, I am sure this would apply to other languages as well.