The challenges are meant to be vague so it gives the ability to interpret the meaning, but what i mean of "meta" is that the game has some sort of 4th wall breaking element on purpose, and for holidays, it can be a holiday about anything, even popcorn day, if you're not sure if you know if anyone knows about the holiday you're inspired by, just simply explain the holiday in your project somewhere where people can easily see the explination. I hope this helps.