I guess escaping would be possible in a similar approach like being trapped in quicksand.
By spreading the weight on a larger surface (e.g. lying down), you apply a lower amount of pressure to a single point, which should reduce the likelihood of fracturing thin ice in the same way it will reduce the rate you dig into soft terrain like snow and quicksand.
What is half bangs doing with that warm water? Does she already think that main nun will fall in the water and is preparing for when they'll fish her out?