Building on top of that: Assuming there were only 2 fear tokens missing for the next card (or even the next terror level), would that newly unlocked fear card resolve immediately, or the round after? If you reached a new terror level, would remaining fear cards be resolved at that new level? I.e., can fear generated during the fear effect phase chain into more/better fear effects?
Immediately. I'm running out the door, so I can't look up the page right now, but it's in the rulebook.