Gil became Baron when Klaus froze himself in Mechanicsburg. He was absent after he went to England to recover Tarvek. But Boris would have been in charge of the Castle. He leaves the Castle to go to Paris https://www.girlgeniusonline.com/comic.php?date=20210716 to inform Gil of the Polar Loard's attack.
So who's in charge of the Castle then? is this where Klaus gets removed from Mechancisburg?