It's actually too FAR from the window. It would prefer to be within 5 feet of the window, so not sunburn. Did you put any potting soil on top of original soil? If so, remove it. Did you firm the new potting soil down the side of the rootball? If not, do it now. When you water it , do you water the entire rootball all the way around? If not, do it that way from now on. Does water come out of the bottom when you water? It should.
Ficus as a group are sensitive to changes in their environment and respond by losing leaves, especially if the light changes intensity. They are grown in greenhouses with very high light intensity, high humidity, and plenty of water. When 1 of those things changes the others should change as well to keep the plant healthy.
Most of the signs you see are responses to those changes and can be partially remedied by moving the plant and changing the watering. Unfortunately the brown spots won't change so you can remove the spot or the whole leaf, your choice
Let us know if you have more questions.
Happy plant parenting.