You will have 180+ random chocolates and 10 hearts. This will take several hours to redeem, so don’t forget to get it done before the quests end. Because it’s not a shop item, conversion ends when quests expire. It is possible to view scenes again in My Room if you are in a rush. 200 cards would be about 6 million CE EXP and likely more if you get Super or Great Success.
For historical accuracy - this turned out to be FALSE. It was possible to redeem everything, including chocolate exchange, in the shop after the event ended.