Have any API let me know the Preferences--Translation--Language has been change?!

Have any API let me know the Preferences–Translation–Language has been change?!

I make the multinational Language Version.Use the PO file and use the “gettext” module.
But I can`t get the Language is been change.So let the Language active need to restart the Blender software .

Have any API let me know the Language has been change?!

Thank you:)!