The Yandex engine uses Yandex.Translate's services.
No other configuration than the API key is needed.
You can obtain a Yandex Key by creating an account and requesting a key https://tech.yandex.com/translate/
The following language codes were taken from the Yandex API page as the languages supported by Yandex.
af Afrikaans
sq Albanian
am Amharic
ar Arabic
hy Armenian
az Azerbaijan
ba Bashkir
eu Basque
be Belarusian
bn Bengali
bs Bosnian
bg Bulgarian
ca Catalan
ceb Cebuano
zh Chinese
hr Croatian
cs Czech
da Danish
nl Dutch
en English
eo Esperanto
et Estonian
fi Finnish
fr French
gl Galician
ka Georgian
de German
el Greek
gu Gujarati
ht Haitian
he Hebrew
mrj Hill
hi Hindi
hu Hungarian
is Icelandic
id Indonesian
ga Irish
it Italian
ja Japanese
jv Javanese
kn Kannada
kk Kazakh