Hey guys, I don't have patreon so I don't have all the info, but from what I understand the way updates used to work is it was alternating between cyanna/rose and haylen/lily.
You're close, but the only major difference is that Haylen and Lily each get their own updates in the cycle. So the pattern generally goes:
Rose & Cyanna (Main Story) —> Lily (Sidequest) —> Haylen (Sidequest) —> Rose & Cyanna and so on from there.
The last stretch of updates have been a rare exception to that, but after Update 18, I imagine it should go back to normal.
So what's going on with haylen/lily, are their storylines over now? Or will it be in update 19?
Going from what I've heard about Lily's sidequest, she's still playing catch-up with the other three girls so her storyline definitely isn't over. Haylen's story is in a slightly weirder spot, where it
could hypothetically be over if N_taii wanted to start wrapping things up as soon as possible for the game's finale because Update 15 left off on a pretty major note for her corruption, but I feel like we will almost certainly get one more sidequest for her.
Update 18 is going to be the rest of the beach quest and I think some more main story as well, so that would mean Update 19 will probably be Lily and then 20 will be Haylen. If you are playing the free public version which comes out a month after the Patreon release... Assuming ~6 weeks of development time per update, I think that would put the next Haylen quest around mid-to-late June for you?
To be clear, this is all speculation. I don't think N_taii has confirmed anything other than the immediate plan for what is going to be in Update 18.