The Iron Claw tribe goblins were supposed to be keeping trolls 

IRON CLAW TRIBE
Martial and almost civilized, miners and crude workers of iron. Use enslaved trolls as manual labor / attack dogs. At war with the Dead Rat tribe.

Which is also reflected in the tribe's main cavern of Kharom, which has troll pens at the top of its "Burrows" cell
These are currently filled with goblins instead of trolls though

The goblins in Kharom's troll pens should be replaced with the intended trolls
And the rest of the cavern, as well as their other cave Pagondha should probably have a couple (armored?) trolls placed in them as tough enemies