I'm quite confused, Satale should be 40 at that time but she looked like she was 25-30 at most in ToC.
Are you referring to Threat of Peace, the webcomic/comic book that portrays the Sacking of Coruscant, the signing of the Treaty of Coruscant and the subsequent attempt to restart the war immediately?
If so, the reason is that the lore behind the game went through revisions between the writing of Threat of Peace and the release of the game. The thirteen-year span between the Treaty and the start of TOR was originally closer to 30 years. So, Satele was portrayed quite young in the comic, and it was hinted that Harron Tavus would become her lover. Also, the look for Satele had yet to be determined, as, apparently, had the looks for Darths Baras and Angral. Later in the development of the game, the lore was nailed down to the current dates, Satele's appearance was nothing like her portrayal in Threat of Peace, and the father of her son became ... someone else (plenty of spoilers on that around).