How to Bend Facia and Undersill Trim around a curve????
The undersill trim should be flexible enough to follow the curve, unless it is a much smaller radius than I envision for this location, but the facia is a different matter. It is obviously not going to follow the curve unless the short return leg can be crimped in some way to allow for the "excess" metal as the curve is bent. A local sheet metal fabricator should be able to sent a length of facia through a rolling machine , but you will need an accurate template for them to work with, and probably not find one that wants to work with a prefinished material. Another possibility, though far from ideal for a highly visible location, is to hem the bottom of a piece of coil stock so you eliminate the razor sharp edge, then bend it around the shape of the already installed soffit trim, letting the bottom edge hang down to form a slight reveal, similiar to what you see with a wood soffit/facia. Be sure the piece can expand/contract freely. Unfortunatly, most curved trim situations result in an ugly creation.