Gang,
If your mean low level is around 2~3cm height from floor level, logically+economy way to rectify this wall leak can say just to repair the bottom wall tiles will do if possible, since lower level still no leak. So you noneed to hack out your flooring tiles. Correct me if I am wrong.
Or we can say, your toilet will not fill up water up to 4cm, but shower water may cause the water fall on the leak wall?