I think routes, prevailing weather, average crew experience, average aircraft age, geographic (topographic features) , airspace complexity and about a thousand other things go into that accident statistics. I couldn't find solid numbers in my 2 min google search, but I would think English speaking countries are probably close to the top of the list in terms of safety.
Plus there is a difference when South Korean maintenance personnel work on South Korean planes flow by South Korean crews, than just sending a US plane to the lowest contract bid in the developing world.
It's more just rich places. Europe, North America and Australia/Japan have very good safety records, and some don't speak English natively.
These places all have highly developed regulatory bodies that communicate with manufacturers and each other. Most happen to enforce English to ease communication on safety related issues.
