flavonsai
Google a leaf shine product. Purchase it. Sray it on to a soft cloth or maybe several paper towels. If the paper towels leaves lint behind, then be sure to use a soft cloth. Maybe something like a dusting choimis or mircofiber dusting cloth. Depending on the size of your tree, set an hour or several hours aside so that you can wipe each leave individualily, gently, to start to remove the calcium deposits. (Make sure it Ca and not fungal).
Or, if your water is not hard, then water the foliage when watering to start removal. In your location the ficus should be fast growing and after a year or so any affected leaves will be able to be cut off (maybe leaving terminal leaves to encourage back budding and braching) leaving only fresh, new leaves in their place.
I'm no ficus expert, but I'd give the second option a try if you don't plan on showing the tree any time soon.
Hope this helps.
Ray