ah i remember this quest from the other side, when you play on the empire you had to kill the gibberlings
have done this a few times when i leveled my league chars but cant remember anything special on this quest
is it possible you have very weak gear?
is it possible to kill all red marked enemies in that area one by one?
in doubt just return later for that quest
PS: well done with linking to the quest-database, instantly knew which quest you meant because of that!