In an urban environment you might also have some reflections that are bright enough in their own right to cause flare problems. I kind of feel that's what happened in the bottom right quarter of #4.
The roundness of bokeh balls at f/4 likely won't show the aperture blade shape when they're more diffused, like the majority in that photo. The two specular highlights in the photo however act more like collimated light and will more clearly show the aperture blade shape.
Regarding focus speed: while it would kind of defeat the small size of the 75/1.9, I wonder if adding a relatively thick ring around the focusing ring would increase its diameter enough to allow somewhat more precise, slower adjustment? As discussed a while back, my feeling is my larger diameter lenses with the same angle of focus throw as narrower diameter lenses are easier to focus, whether via RF or visually via EVF. Another compounding factor for the 75/1.9 might be its wide open residual SA subtly blurs the plane of focus compared to a higher contrast, better corrected lens, making visual focusing via EVF potentially more tricky when combined with the fast focus throw.
