onClientLocalizationChange

[Hydra]

function b()
  outputChatBox("Your language changed succesfully")
  end
addEventHandler("onClientLocalizationChange", getRootElement(), b)

I'm not sure if this event helps anything because you have to disconnect from the server to change the language. But I will still leave this suggestion here

[ds1-e]

Better idea would be to move it to GitHub.

https://github.com/multitheftauto/mtasa-blue/issues