I'm not completely sure from an outsider's perspective about which catalog you're referring to. Essentially, here's how it works.
The consumer catalog sets up the LEGO kits in the minds of the public, so they can go to the store and pick out what they want for their kids. Or their parents. Or themselves As you'd expect, this catalog is not done yet.
The retailer catalog basically does the same thing; the most significant difference is that it offers the choice to direct retailers before the consumers, so that the average small toy store (any non-name brand) can decide what they want to order in to maximize profit. Direct-to-consumer kits like the 75192 Falcon aren't in this catalog, because everything about their distribution is controlled by TLG on the corporate level. That's why your local LEGO store won't even know about them until the release draws near. For the 2HY 2018 slot, these catalogs are probably not yet done, but I could be wrong.
There are other things that could be referred to, or even straight-up be a "catalog" as an addendum to these two; I really don't know, because I don't work at TLG. It likely differs from company to company, but I would suspect that the Billund/Enfield corporate side of the group puts together an internal "catalog" for advertising and regulatory (legal) purposes. This is nearly guaranteed to be done, but it isn't likely to have been seen outside of the company or an affiliate along the lines of Advance or Cartoon Network. If the leaker is legitimate, I would be very surprised if he did not work at one of these. They did say that there would be a cartoon...
Again, thank you for understanding.