The Payoneer USD account can only receive USD. More than likely to the same analogy the EUR account can only receive EUR. Since your earnings are in USD on CB, CB should send EUR. It will turn out soon, if it works or not.
For international direct deposit (XACH) CB has this in the terms: "ClickBank may charge a nominal percentage above its competitive, negotiated currency conversion rates. This amount represents a portion of the difference between the wholesale exchange rate we are able to obtain and the available spot rate on the day at or near your payment date."
Why do you want to do it like this though? You can have one receiving account in every available currency on Payoneer. Why not simply receive USD to the USD account and if you want to spend or withdraw the funds in any other currency, the currency conversion will happen at that time. This way there wouldn't be a nominal fee above the wholesale rate deducted by CB.