Yandex Translate is no more recommended, cause they removed free service.
- Go to Configuration->Locale and add field of type string, named "yandexLanguage"
- Create account for Yandex Cloud here and optionally activate free trial
- Create a service account with proper permissions
- Create API key for this service account as described here
- Go to Settings->Translation, paste your API key there
- Go to Database->Localization and for each locale fill "yandexLanguage" field with the right language
- Choose any table with "localization" (Locale) or "localizationSingleValue" (Locale-S) types and string/text field type. Click on Setup and choose Yandex as translation service. Choose your source language and destination languages.
- Click "Run" to translate several rows. Click T↑ to translate one row to all locales. Click T↓ to translate current row to one locale