Things we know about this prop book, which has been a great source of information for the TV canon:
1 - Writer Bryan Cogman did indeed write it, making it more "official" than if it was only written by the props guys.
2 - There were only ever eight pages of unique content, covering four Houses: Umber, Royce, Targaryen, and Baratheon - two pages of content for each House.
3 - Cogman did thoroughly research it...as much as possible. But no information exists for some random Umbers...so he made up some names. Like "Monica Velaryon". I don't know if he consulted GRRM about some of these. So we should take those non-canon names with a grain of salt (then again...Willem Lannister and Viola Redwyne aren't exactly book canon either).
4 - I've rewatched the scenes, and near as I can tell, no pages from House Royce are ever visible. For each of the remaining three, two distinct pages are seen...though sometimes only in closeup (particularly the Baratheon one, which only focuses on a section of a page). So six unique pages are visible on screen at one point or another...though they're not always in focus and sometimes the camera has zoomed in to show only half of the page. The two pages for each House can easily be told apart: one will have a sigil, the other will not (There' one with the Umber sigil, then one with just the word "Umber" in bold at the time..same for the Baratheons and Targaryens).
Okay...I'm reading through this, and based on Cogman's interview information, he said that he did what research he could, but he had to make up a lot of names in the games. For example, all of the information about Aegon IV, Naerys, Daeron II and Daenerys, intermarrying with the Martells, Daemon Blackfyre and the Battle of Redgrass Field....all of that is book-accurate.
The Umber stuff, meanwhile, is largely invented. And normally I wouldn't mind, because if even Martin hasn't thought that out, it's a blank page to invent something.
....but some of the Targaryen page are really messed up - you see he only made about eight pages of content, then the props people just repeated it over and over again to fill the book, at times mismatching things.
For example, at the end of Targaryen page 2, it lists "Aemon Blackfyre, the Dragonknight"...younger brother of Aegon IV (who was...not a Blackfyre)...and "born to Viserys II" (which...really makes him not a Blackfyre). Yet he died defending Aegon IV from assassination? (Dragonknight). Looks like he wrote in "Blackfyre" when he meant "Targaryen".
So some of these names are just invented and I think their canonicity is dubious..."Serena Blackfyre" is probably just a placeholder name he made up (Daemon Blackfyre married a peasant girl?)....and Viserys II's wife is given as "Visneya Targaryen" (almost certainly he just made up a similar sounding name, which is kind of implausible for two married people to have a priori....Viserys II's queen is one of the few we know absolutely nothing about, so this is probably one of the cases where Cogman needed to "fill in the gaps".
At any rate, I propose that we only use the book as justification for including book characters into the wiki (i.e. "Daemon Blackfyre")...but that non-canon names are probably just made-up placeholders Cogman came up with -- and some things like details of how book-characters died (which we don't know yet in the books) he just had to make up.
Therefore, I propose that we disregard many of the names seen in the Lineages, which do not appears in the books, but which were just placeholders that Cogman made up and which would only be visible in freeze-frame. They introduce too many complications.
However, I think we should postpone dealing with this until the World of Ice and Fire sourcebook comes out in just a few months, given that it will give us the definitive details on the Targaryen and Baratheon genealogies and histories. Better to just wait for the sourcebook in order to fact check how it differs.
But I think the original idea of making an article for every new, non-book name appearing in the prop should be abandoned.
Moreover, I major point I want to make is that just because Maester Malleon wrote this book in-universe, does not mean that it is objectively accurate.
The World of Ice and Fire is written under the conceit that it is a book created in-universe by "Maester Yandel", as a popular history - it's what educated people generally know as history, but not the true, secret reasons why certain things happened (i.e. Joffrey would be recorded as Robert's son, with no mention of the incest between Cersei and Jaime).
Similarly, Maester Munkun was simply mistaken about which dragon killed Ser Swann, Vhagar or Syrax.
So the in-universe explanation we can later give for why "there is no "Monica Velaryon" in the TV continuity or book continuity" or "there is no "Aemon Blackfyre, son of Viserys II"....is that, similarly, "Maester Malleon", the author of The Lineages and Histories of the Great Houses of the Seven Kingdoms, simply made a careless error and accidentally swapped names.