OWOX BI converts Yandex units to your Google Analytics view currency using the Yandex units exchange rates.
If the currency you use for your Google Analytics view is not listed there, then OWOX BI converts Yandex units by this process:
1) Yandex units are converted to USD using Yandex rates,
2) USD is converted to the currency of your GA view using the Open Exchange Rates API.
Note: How does the regular currencies (not Yandex units) conversion works is described in this article.