While I am a fully paid up player of the HBS videogame, I am not really a fan of a canon Arano Sourcebook, and would prefer if it was left as an alt-universe.
But putting that aside, and accepting there will be no ComStar hid them plot, what will actually need to be considered reconned? I mean the Interstellar Players and Periphery type books don't mention this new faction obviously, but they were always pretty explicit that various unmentioned Periphery factions didn't get covered.
Strictly speaking in terms of 3025, not much. At best, I think the Regis Roost Touring the Stars book is the only immediate contradiction with the game, and I doubt that'll be revoked after just coming out.
When you move beyond that it gets trickier. Two Aurigan worlds end up in Taurian hands. But even then, current canon establishes that region was home to several Taurian and Capellan colonies abandoned during the Succession Wars, and notably the Concordat mostly didn't go back there, even when the Taurians and Canopeans were actively colonizing the region (the fronc reaches don't touch any of the Aurigan worlds) and these worlds would have already proven viable. There's room to say it was because a political structure already existed there and wasn't interested in joining the fold.
It would still be a retcon, but not a 3025 revised level retcon. Maybe not even a "Fotch pulled another bit of nonsense out of his ass" level retcon (I'm looking at you, Free Guilds!).