A related bug (or more likely intentional disregard in the development cycle): the Maple Administrator in Southperry does not provide Bean Porridge in return for Red Envelopes (indeed, she isn't even aware of the event), despite the description on the event page: It's hardly anything very important, but I thought it worth mentioning. I imagine most people living off Maple Island will prefer large sacks of money in favour of porridge anyway.
As someone who has an islander, I'd rather be able to exchange any islander-useless event items for pet food! Having a pet would make training my islander a whole lot more relaxing and enjoyable, but since ~storage was disabled for Maple Island, having a pet there isn't a realistic option. (Not that I had one before - it's just something I contemplated.) I'm sure other islanders have their own ideas on what they'd want, too. As far as I know, Red Bean Porridge doesn't have any current useful function on Maple Royals (beyond a quest that needs it) as the HP-reducing maps don't actually reduce characters' HP.
Perhaps, but collecting things is fun all the same! For what it's worth, given the daily income of eight thousand NX you should be able to keep a pet alive with the closeness food from the Cash Shop; it recovers the entire fullness of the pet.
I'll be closing and moving this thread to "Closed Bug/Glitch Reports" once the event is over, but for now, it's useful information for anyone who wonders why they didn't get anything from their Red Envelope.