And Shadowheart and Lae'zel both get their weapons out, too.

"—bloody hells."

There were other goblins starting to surround them but they stop, uncertain, seeing the group be a lot more prepared than expected.

There will just be a little red squirrel, sneaking around behind those reinforcements, don’t mind her. Much less important than those adventurers up there. Is this plausibly a number of goblins they can in fact take? Good, good. Then she’ll just stay an adorable woodland creature for now.

    "...we, we've got you outnumbered," a different goblin squeaks.

"Oi, shaddup, idjit, he's got a knife on me!"

"It's a githyanki dagger, actually," he singsongs. "Now, I could have killed you. I walked right past your guards and got up here and not a one of you realised. If I wanted to kill you you would die one by one and not even notice it. Ivy, dearest, do you want to demonstrate just how completely unprepared for us they are?"

She unsquirrels, almost directly behind two goblins on another roof entirely.

“Hello~” she says, picking up Astarion’s singsonging cadence.

"Holy fuck," cries one of the goblins while the other one whirls around to try to charge her in a panic—

There is a druid cantrip known as ‘gust.’ It summons a bracing gust of wind. The goblin charging her is charging uphill, up ceramic roof tiles.

Can the goblin make the required strength saving throw, to not get thrown off the roof?

(Lae'zel approves.)

(Shadowheart approves.)

(Astarion approves.)

...the goblin cannot in fact make that strength save, no.

"What do you want," wails goblin #1.

"Just to pass. Maybe ask a few questions. And not be filled with arrows. You would regret trying to fill us with arrows very, very much."

"O-o' course. Ya heard 'im, boys, let's, uh, let 'em pass, like."

There's some grumbling but yeah they're pretty convinced.

"Wonderful," says Astarion, drawing the dagger away from the goblin and straightening up.

Ivetrielle beams, then makes her way down to join Shadowheart and Lae’zel. Are any of the goblins going to change their minds and attempt murder as she does this?

No, though one of them does grumble something like "Prob'ly didn't even have good loot anyway..." while shuffling over to check on their compatriot who fell from a roof.

She will not dignify that with a response, and will also not scurry over to check on the goblin she threw off a roof. But she will check. Just, subtly. From over here. Still alive? Yes? Great.

In an undertone to the others, she asks, “Are we not going to ask them questions about… things?”

"I think he is asking questions," replies Shadowheart, pointing at the roof where Astarion seems to have retreated to a corner and sat down to have a quiet conversation (?) with two goblins. "I don't know what questions we are meant to ask. 'Where is the druid?'"

“This is true. I don’t really know either, it just was the stated goal. Talking to animals is much easier than talking to people. I can’t just bribe goblins with nuts and raisins.”

...she's kind of noticing that she gets this feeling of having been conned every time she goes along with Astarion's plans.

"You, k'chakhi," she barks to the goblin Ivy pushed off and their friend.

The goblin squeaks.

"Y-yes, sir!"

"Where is the druid?"

Both goblins stare at her and blink slowly in unison. "Th-there?" one of them tries, pointing at Ivy.

This was utterly predictable, but it still causes her to crack a smile. That being said, it does give her an idea, actually. She can do this talking thing! Really! She takes to animals all the time, the skills should carry over at least a little.

“Do you know where the band of idiotic mercenaries got accosted, and where any prisoners might have been taken?”