Next dialogue to spacebar, and exiting dialogue ?

[Niwashi]

Pretty much all cutscenes that are locked behind a quest are re-watchable from your inn room at "the unending journey" (a little book on a desk).

This is false. Only a tiny fraction of cutscenes are available through the Unending Journey. Typically, it's just the ones with impressive cinematics that appear there, while the more common type that are mostly dialog with limited actions (like what would be available through emotes) do not.

If the cutscene occurs at the completion of a quest, you'll be prompted at the end for whether to complete the quest and accept the reward or not. That gives you an opportunity to cancel without completing it, so that you can view the cutscene again. But this isn't available if the cutscene occurs at the beginning or middle of a quest.

If the quest involved is a sidequest and you haven't completed it, you can cancel the quest and start it over in order to view the cutscenes again, but that doesn't work with MSQ cutscenes, since main scenario quests can't be cancelled.

So there are a lot of cutscenes that you simply lose if you skip past them, and you can't see them again short of getting another character to that point.