Kayda will also mention that they didn't have a bridge- smart though he thinks that was, Kuylen would have thought such a thing too slow (he didn't have anyone to float it into position). Instead they brought ladders- easily made, one carried between two men, six in total. They jumped into the trench but could quickly climb out.
"They used them on us!" says Kayda. "But Kuylen took six men through the gate and back up and round into where the men manning the holes were and silenced them. And sure, we were armed."
But indeed, Kuylen didn't take anything that would slow people down- his whole plan was to be through the gate before it closed.
He had other things on his side- the defenders were not expecting an attack (whilst with you guys, your use of force powers had made them wary). The guard was smaller, and he didn't hit them on a guard change so there wasn't a same-sized army on the far side.
Just an idea for dealing with the trogs - I'm assuming being baddies we all have intimidate to a certain degree. Well using Rah's unique ability to make noises could we scare the trogs away using intimidate and strange roaring noises echoing around the caverns/tunnels? I'm thinking along the same kind of lines as Obe Wan scaring the sand people away from Luke in ANH.