Right now she's not having any issues with breathing that couldn't be chalked up to exertion from their escape and pain, but the reason the tail didn't go all the way through is because it's lodged right under her ribs. Anatomy isn't her forte, but she knows that the lungs are under the ribs, and if the tail moved and hurt one of her lungs she'd probably be in more trouble from that than from the possibility of bleeding out.

Nill glances at the rope, considering it, before nodding her head in agreement. It does in fact look like something may have bitten at it at some point, and her arm is probably bruised underneath, but it's proved sturdy so far, and could probably be relied on for this.

"It should work. We won't find anything better."

If nothing else, the xenomorph was polite enough to aim for the side that was already not looking brilliant. So at least she doesn't have two bum sides. Though the movement looks stiff she lifts her hand to try and undo the knot in the rope, but her fingers slip, still slick with blood, and it only seems to frustrate her.