Are you saying that aviation is inherently less safe in non-predominantly english speaking countries?
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.
I am going to say though flying is safer in the developed world. US based passenger airlines did not have one fatality since February 2009.
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.