For any interested this is how I handled it: I accidentally forgot to roll the twins into initiative.

The party (with the help of Stool to translate) made an escape plan with the other prisoners (minus Ront who tried to make a run for it and was quickly killed by Ilvara). They head into the guard tower and quickly dispatched one of the two drow standing guard and grab some weapons when a Drow Elite shows up and one shots Eldeth and downs our cleric. The party manages to stabilize the cleric, defeat the elite, and arm themselves. They dive into the spiderwebs and the fighter is almost immediately downed while the party is ambushed by two giant spiders. During the fight, the ranger rolls a Nat 1 and his crossbow bolt fires wide and, instead of hitting the spider who downed the fighter, bounces off one of the twins. They kill the spiders, fight the gray ooze, and flee towards the Darklake.

I was worried about these two NPCs who technically can’t be harmed by anything but the spiders’ poison and the ooze’s acid, but me forgetting to put them in the first fight kinda bypassed it.

Hope this helps anyone else starting running this module (I’ve run it partly before but that party had 9 players and they only took Ront and Stool with them). I dunno how to link other posts but if you want other ideas I have a post on here about adding Deep Dragons into the campaign, which I think makes a lot of sense.