Extension fix

can someone help me fix this extension for kirka.io? it got outdated when the mv3 came out, its supposed to let you swap out the sounds, gun models, player textures and the gun skin texture, but for some reason after mv3 came out its not working, i tried every AI to help me fix it, but all seem to not work, they only fix the custom character swapper, i want to fix the sounds/gun model/gun skin texture, heres a vid on how it should work, and the extension ZIP

https://www.youtube.com/watch?v=rfqQzUDw1K8&t=125s