User blog comment:Hayashi H/Spring 2016 Event Guide/@comment-26486243-20160510015914

The debuff conditions have been confirmed by the devs on Twitter today. In addition after 13 May the number of nodes at which Oyashio drops will increase, so it may not be as necessary to farm her at L any more if you clear the map before getting her.

Due to IRL conditions I cannot update the guide for the A G debuffs now, so they'll be up in a few hours. Also since the nature of the debuff is to weaken Central Princess's vulnerability to airstrikes, it would seem the Zuiun Nuke is actually intended behaviour.