There’s no way the journal has everything about Laugh Tale in it, because there’s absolutely no reason for something like that to be introduced to the series. No out-of-series reason for Oda to introduce something like that, no in-series reason for Oden to write it.
It’ll just be a hint about these truths, same as we’ve had plenty of times before, with maybe more info than before now that the journey is nearly over. But just a bit, specifically about Wano and the Kozuki, not “this is what the will of D is, this is what Imu is, this is what happened in the Void Century, this is what One Piece is.”
Robin hasn’t been punted out of the crew for knowing what Shirahoshi is, Franky isn’t gone for knowing how to build Pluton, Yamato’s not getting ruled out for having some Wano knowledge.