The answer is that we ended up putting our efforts into the books last couple years and then... never got around to making the sequences. BUT this year I've been preparing them for the past couple weeks, and planning to launch them soon.
It looks like the sequences from the 2018 book (like Curiosity) are both 1) not visible in the Library and 2) made last month. [The Sequence The Less Wrong Review is of announcements, not the posts from the review.]
Is there some way to see these? Or are these the same sequences Ray says he's planning to launch soon, and I should wait until then?
I just made a series of attempted actions on the site that ended up with me being confused. Am I missing ways to use the site, or are these ways missing?
I was reading the page for the 2019 review book launch, and someone commented that the table of contents has no links. I thought to myself, I'll be helpful and post a comment that is a link to the 2019 review sequence! That is, the sequence page that is a list of all the posts that ended up in the 2019 review books. (The reason I thought this page existed is because I had recently found the sequence page for the 2018 review books.) I then searched around for this page by googling, and failed to find it. I then tried to go on the LW home page to see if there was a list of sequences. I saw "Library", which lists "Core Reading", "Curated Sequences" and "Community Sequences", but even after clicking "Load more" on Community Sequences until there were no more, I didn't see the Review sequences I was looking for. I thought for sure I had seen one, though, so then I went to a specific post that I thought I saw it on (Arguments about fast takeoff) and sure enough there was a link for the Alignment sequence at the top. This is one of the five books in the 2018 review. But it didn't itself contain a link to a higher-order sequence of all five books, or anything. And it isn't listed on the "Library" page.
So, it looks like the "Library" page doesn't list all sequences? Is there a place that does? And is there a sequence for the 2019 review? (If not, I'm happy to make one.)