"Renders the app useless"? What do you mean? You can't use Amethyst because of translations? That's weird.
Discussion
The problem is that you cannot turn it off. I am forced to read everything in English, which means my own messages in Dutch get translated as well. Or i can put the app in Dutch, where my own messages get mistaken for Afrikaans as soon as i am being just a tiny bit creative.
Make translation optional, and it would be fine.
Oh, Just add a Dutch keyboard.
Or click on the language and select don't translate from Dutch and Afrikaans when the translation message appears.