A friend complained to me recently that after Big Ben she had not received her "instant level," and it seemed like the game never gave her an "instant level" when it said it would. :( In other words, the phrase "instanced level" was not computing. :? This is an intelligent adult friend whose first character is a Grandmaster and second just got to Mooshu.
Computer geeks (like me) may know what an "instance" is, but I doubt people from other backgrounds (including, say, middle school) get any clear idea from the name. "Level" is used by people to describe what level their wizard is, and "instanced" means, well, who knows. If you don't know what an instance is, saying the instance will "reset" doesn't tell you much, either.
To be people-friendly, don't name them after what the code does; name them after what the player does. Maybe call them "block quests," because the player has to complete them in one block of time. The help/hint could say your progress in the block will be saved for a short time if you exit and return, but if you stay out longer you will have to start the block over.
This is really a good point. I hadn't thought about it, since I (being a geek) knew immediately what it meant. Oddly enough, my kids seem to have figured out what it is as well from context and experience, although now I'm wondering if they know what the word really is, or, like your friend, think it is something like an "instant level."
Try to give them a different name and you'll only confuse people who come from other games. Some terminology choices are rather unfortunate, but once they're widespread enough, we're pretty much stuck with them.
In your friend's case, it might have helped to point out the difference in spelling between "instanced" and "instant". It's really not possible to name everything so as to always avoid eggcorns.