All Magnifi transactions are based in US Dollars. Magnifi call earnings deposited to an Expert's Stripe Balance are transferred in the Expert's native currency, as selected during Stripe account setup.
Similarly, any refunds issued to Callers on behalf of an Expert are refunded to the Caller in USD, but deducted from the Expert's Stripe Balance in the Expert's native currency.
As per the Calculating foreign exchange rates section of Stripe's Docs, exchange rates used for conversion vary and usually include a spread charged by financial institutions (e.g. approximately 2% for CAD/USD conversion).