Considering how we have a Star Trial running, most likely next Revival and Event will be Unit Farm ones. Sooo, Odette?)
we just had a farming event with Maribel's revival, on the other hand, it has been a time since the last colection event, so i guees it's up next. Knowing that, it should be Karma's event (assuming revival), but then again only the devs can decide that
Collection revivals do not work the same way as farm ones do. You collect crystals and buy the girl + copies with them. I still keep praying they'll turn all Lianas into Illys and then throw the Liana event at us...