Why do you say so?
Imo it was plausible to do so with spare piano wires (getting them out from a piano is possible but much harder and cumbersome) and the damage was reasonable realistic considering how fast they were moving. Also liked the fact there were broken glasss bottles all over the place, probably to avoid people crawling and using the tables for cover and becoming instead a hindrance for atackers. The defenses were designed not to kill but to stall and allow reloading time with the crossbow. Actually pretty smart, since she probably has only a few extra bullets and she can reuse the bolts instead