i'm sorry if this is an obvious question or if it's been asked before but if Meenah killed all the alpha trolls with a bomb, why did her death appear to happen so much later than everyone elses? Aranea says at one point that she's been waiting for Meenah for a long time, but wouldn't they have all died at the same time?

Time works differently in the Furthest Ring.  Just to prove this,  Dreambubbles didn’t exist until long after the Pre-scratch trolls died.