Even with thinned numbers, the Zhents alone with 1 or 2 goblins can wipe you out. If I could see what each was, I'd be able to balance it far better. Thinking the level one goblins are okay, they don't have a class from what I've seen. The novices seem to actually by a mix of cleric, and wizard. Do to ones use of guiding bolt, and another enjoying burning hands. Not sure if same novice casted Shield of Faith or not. If they were just leveled up. Take a normal goblins hp, from monster manual, and double it. The fight would be manageable until the Zhents come marching on. I can see Zhents having a fighter, and a ranger/thief with the trader being maybe a warlock. Right now it seems they have access to both weapon skills, and wizard abilities. Though think some of it is a potion of invisibility. Not sure going to explore from a previous save point, and try again when higher level.
Pretty sure the novices are clerics. I honestly have only seen them cast cleric spells. Maybe they had a scroll on them? They dont seem to be class restricted and enemies do like to use their items. Ive seen npcs basicly use consumables in their 1st turn so you will. never have a chance to loot it unless you kill them before they get to use them. Which is kinda sad. In bg1 and 2 enemies often had consumables on them as well but rarely did they use all of them right away. You often could kill them and still loot some of them.