Sorry for the delay. Quick question: maybe it's intended to be self-evident, but once the ropes are tied together, are you heading down? All the PCs can do this without issue as they have the Adventuring Proficiency. Patransa and Tallad will have a harder time of it.
Yes, that is the game plan I believe. We can try to do something to make the rope easier for them to climb if you want. Knots or something every so often or try using one of the goblin ropes as a safety line and lower them down first.