Moonqueen's ultimate will hit what they originally could hit. The vision deminished is only a visual effect, not an actual change of the fog of war. Hence the reason you can autoattack creeps not in your line of sight during the ultimate, which is not a possibility normally through fog of war.
In fog of war, your hero AI don't know that something is right out of your vision. Hence moonqueens ultimate don't work.
During Dark Lady's ultimate, your hero AI still know exactly what is going on at it's normal vision. It's only your vision who is removed, not your hero's. You can also cast spells on targets you cannot see during the ultimate, as long as you targetted the spell before the ultimate was put on.
There is a distinct difference between fog of war, and vision deminishing from Dark Lady's ultimate.