Like other said. Reissue events are always about sealstones or some variant of them - basically a item that drops from chests in the maps, and is given once when map is 3 medalled.
As for this event stats, since I posted I gone up to close to 17K2 stars and 374 bells (which are worth close to 5K8 more stars - so total 23 out of 34K5 I need to fully clear shop).
So I need 11K5 more stars farmed across phase 2, which is around 1640 a day, with a bit over 180 average stars per better boss that I didn't spawn, I would need to poke 9 of not spawned by me p2 better bosses, or nearly 16 of p1 special ones.