I'm hoping that the last task won't be help fantasia x3, but I don't get how you would miss out on points from it, since you can just tell lilia you don't want to help fantasia and it'll still count as being a completed quest. It'll still kinda suck to miss out on conecakes/potatoes, but I don't think you'll lose points!
Maybe if you could do multiple summer festival quests at once and chain them like dailies, that could help a bit.