If you like using the auto-translate feature and you get errors. There are chances, that my Yandex API key reaches limits (shared with everyone).
I wrote an article on how to get your own API key for free, so you will never reach these limits
https://mastalab.app/2018/08/26/get-a-free-yandex-api-key/
Also, if you are not aware, the app uses MyTransL, a small library that I built, which has the particularity to obfuscate sensitive data before sending them to the API: