I couldn't find this suggested yet so I'm giving it a shot.
I've been noticing a lot of people trying to buy/sell/gift large amounts of Candy Hearts. And I'm in the process myself of receiving a few thousand Candy Hearts from a friend which is taking a few hundred trades at 10 hearts/trade. Since this same thing happens with every event which has its own shop/currency I thought maybe something new could be implemented.
My suggestion is to add a few items in event shops that allow a user to trade in their currency and purchase an item worth a set value of currency to sell/gift.
Example: In the L'amour Parlor, add an item called 'Large Box of Candy Hearts' priced at 250. This item would have the 'open' feature similar to and would give 250 Candy Hearts. This way it would be much easier to transfer currency to other users during events.
Currently selling: