When placing the 7th token on Stage 1B (Grimbeorn's Quest). a lot of things apparently happen.

1. The Carrock becomes the active location.

2. Stage 1 progresses to Stage 2 (Against the Trolls) since it has enuf tokens (7) to be cleared.

3. Stage 2B stages into play the 4 Unique trolls.

Is this the correct sequence of events?

Yes, all correct. You start 2b with Carrock as active location and trolls in staging.

Thanks for the help!