I understand your frustration. Sadly, those are the only players queueing in that particular amount of time. If it's even possible, it will take hours. Not one or two, but literally 4-10 hours to gather 24 players to do this singular run. However, you can notice that players in fewer parties deal a lot more damage than they individually do in a larger party. That's because of the echo system they implemented in those instances, which scales the strength of players (In terms of HP, healing, and DPS) based on the number of players that are active there. The fewer they're. The stronger they're.
I have already suggested the idea of moving Delubrum Reginae, Dalriada, and even Castrum to the duty finder when 6.0 hits to help players doing them, and hope that the devs will find a way to help in that regard.