Manual language download for offline devices

I am keeping my Supernotes strictly offline. When I wanted to change the default auto recognition language, I found I cannot as they need to be downloaded. Is there a page where I can download them from, as I can download the firmware and install it manually? Also how can I access the Supernote app Atelier etc manually? I have got no problem with possibly manually installing them. I just want to keep my devices offline and use them fully. And up until now this worked great.