Wasn't Adas the original Sith King? Graush came after Adas.
And Malgus went into the Unknown Regions? Thought that was Revan.
You don't have to rewrite canon, just retell canon. Enough of the events of the various timeline entries have been told to give a basic story in videos. For example, the only thing new in BW's entry on The Great Hyperspace War was that the current Sith Emperor was alive and serving in that war. Or for Exar Kun's Sith War, that the entombed Sith Lords of Korriban favored Exar Kun but denied the Sith Emperor for unknown reasons. A retelling plus a tiny thread on the tail end that ties to the game.
Sorry for the skepticism. A while back someone cross-posted on several TOR forums about "a mysterious transmission" that only turned out to be stealth advertising for a guild. Since then, I've been a bit leery of hidden possible guild spam.
If you stuck around and chatted beyond just promoting your guild and stuff, that'd be cool.