Castrum isn't all that cutscene heavy compared to other dungeons, there's really no reason those cutscenes are still unskippable. Ultima's only long cutscene is the phase transition one, and those are always unskippable (and Ultima isn't even that much worse than some others, like Cinder Drift, anyway)

The only issue is Prae, and frankly I don't get why, when they were already reworking it, they didn't manage to trim the cutscenes down a bit more. Like, even getting it down to the usual start-of-instance and a pre-final-boss ones would've been possible with some creativity, but even if they didn't want to go that far, surely they could've done more than this?