Same poster as above. On reflection, the next event was the anniversary with a whole bunch of event girls up (more than the regular ones), so it's not entirely surprising that I ended up with one. The point about clarity of communication still stands though.
It was part of the news announcement for that event, not a general announcement. Nothing that was part of an events announcement has ever been applied to something that wasn't that specific event, so I would assume it's clear that it's part of that event and not a global change.
darn, and here I was planning to use my anniversary kobans on this event (I tried one spin in the anniversary event, but go a regular girl. so I saved the other for this event) If I had thought the "only event girls" was no longer in effect, I would have tried another at the anniversary- (20 in 35 is much better than 3 in 18, but not as good as 3 in 3)