Everybody, we seem to have missed something.
First of all, there is no doubt that Nadia knows about witches. It's clear from her demeanour and her reaction when our girls said they knew about soul gems. More importantly, she seems to be aware of the general zero-sum nature of the cycle of despair, which is why she brought up the example that she did - girls wished to avoid the consequences of magic use, so the consequences were passed on to other girls. The system protects itself from abuse.
Which makes us ... strange. What's our drawback, Nadia is (reasonably) wondering? We seem to be cheating the system in a fundamental way.
However. However. Nadia knows about Kyuubey. The first big question that we need answered is, is the cycle of despair an unavoidable consequence of the metaphysics of wishes? Or is it imposed by the Incubators due to their hope/despair double-dipping?
Another interesting thing: we know for a fact that the Wish system is open-ended. Wishes can close over the cyclical consequences of their desired outcomes, because that's exactly what Madoka did in the series. It's like a Hilbert Hotel - a wish can be made to outrun its own drawbacks. This is the second big question: is our wish one that outruns its own drawback? Or is there a hidden drawback, that we don't know yet?
Do we know if our grief is negentropic for Kyuubey? If it isn't, I could see it try to use that as a griefbomb against us at an opportune time.
