Autocalculated price field depending on language
Ok, I managed that with computed field. Money field was not needed.

In computed field I've posted code:

 $exchange_rate = CurrencyExchanger::load('PLN', 'EUR'); 
 $netto_price = array_pop(array_pop(field_get_items($entity_type, $entity, 'field_name'))); 
 $entity_field[0]['value'] = bcmul($exchange_rate, $netto_price, 2);


It calculates currency in fly from currency module.