Page 343, left hand column: "...also placed the tiny worlds of Hell’s Paradise and Heraklieone on the red list. Marik could not fathom the logic behind some of those deep strikes; he’d never even heard of Heraklieone before..."
Problem: According to other sources, the system has been named variously Herakleion and Herakleione, but not (so far) Heraklieone - although Herak-lie-one might be a deliberate pun/hint.
Page 17, Star League Era Factions List, Age of War Sub-Era (2300-2570)
I like this table (a lot) but it feels like there are a couple of entries missing. I know there's a caveat that there were other, unlisted powers that are absent because they were militarily insignificant, and some of the early history of the Age is a bit of a chaotic, but would it be possible to alter the faction list slightly? My two suggestions are that the Capellan Hegemony should be included, as the Hegemony appeared in 2270, and was responsible for conquering the Ingersoll Concordium in 2272 and attacking the St Ives Mercantile League in the 2280 before ending up at War with the Sarna Supremacy from 2304-2309/2310. It could be included by amending the Capellan Commonality line to read "Capellan Hegemony/Capellan Commonality : 2270-2366"
The other change I'd suggest is to the Tikonov Grand Union. The original Tikonov Union seems to have been a nation in its own right, as well as (later) some sort of mutual defense organization that included the Chesterton Trade Federation and the Chisholm Protectorate, and was at war with multiple factions at various points, including the Terran Alliance. Can I suggest amending the line to read "Tikonov Union/Tikonov Grand Union: 2177-2366" with a footnote stating that the Tikonov Grand Union includes the Chisholm Protectorate (2265-2335) and Chesteron Trade Federation (2193-2357)? That way, both earlier nations are incorporated from the dates they appear to have come into being up until the conquest of the Chisholm Protectorate by the Terran Hegemony and what looks to be the date the Sarna Supremacy had finished conquering the Chesterton Trade Federation (only to then be attacked by the Federated Suns, targetting former CTF worlds).
Page 17, Star League Era Factions List (2571-2781)
The Illyrian Palatinate is missing from the list - although only two of its worlds appear on the 2571 map in Handbook: House Marik, it appears as a nation in the 2596 map in Historical: Reunification War (p. 158) and the maps in the two Historical: Liberation of Terra Volumes. It doesn't appear to have done much of anything, but as the Oberon Confederation gets a mention, despite apparently consisting of just three worlds before falling apart after twenty years, it seems reasonable to include the Palatinate. On a similar basis, Tortuga Prime appears on the map of 2596 in Historical: Reunification War (p. 159), and the Tortuga Dominions appears full-formed on the map of 2765 in Historical: Liberation of Terra Volume 1 (p.11), so it feels like the Dominions should get a mention too - particularly as it seems to have been a bandit kingdom forever.
Page 22, Early Succession Wars Sub-Era (2781-2900)
Again, the Oberon Confederation appears in its early-three world form, but no Illyrian Palatinate or Tortuga Dominions.
Page 22, Late Succession Wars Sub-Era (2901-3049)
Again, no Tortuga Dominions, although the Greater Valkyrate and the new Oberon Confederation both get a mention - maybe the Tortuga Dominions don't have the right press agents?
I'm also not sure what the criteria are for including the various Deep Periphery nations, but it seems a little odd that the Hanseatic League and the Castilian Principalities/Umayyad Caliphate get mentioned from the Early Succession Wars onwards, but the Chainelane Isles doesn't, given that it's been around presumably as long as the Oberon Confederation, at war with itself for most of that era, and in more recent sourcebooks has started appearing on maps of the Inner Sphere.