After selecting the card to trade, you can choose language or flair by tapping the “Edit Card” button.
■Steps
Social Hub (the middle button at the bottom of the screen) > Trade > Tap “Trade” on the friend you want to trade cards with ＞ Tap the card you wish to trade ＞ Tap “Edit Card” ＞ Tap “Set” for language or flair ＞ Select the desired language or flair and tap “Select” ＞ Tap “OK”