I am not sure if the leaf damage is caused by a fungal infection. The damage is a bit too focused in one area and the shape is unusual for the common fungal infections. My guess is that too much sun combined with stress from the transplant has caused the lower or oldest leaves to decay. The clue is that this indoor plant looks like it is sitting outdoors and plants do not adjust quickly from the low light of indoors to outdoors in the summer. The Neem oil won't hurt and could be helping so continue to remove the infected leaves and water when soil feels dry and perhaps new growth will begin once the plant settles in to the new environment.  If I am wrong and the plant continues to decline after several weeks please send more images and perhaps I can help to discover the reason for this decline. Keep growing, Marianne Binetti