hello Roger,
this body cam still was shot 6.5 minutes after the first shots were fired and shows the position of the sun:
here, the reflections in the windows are simply reflections of the bright sky…
in the following picture, the white reflection in the rightmost window is simply the white roof of one of the barns:
if you zoom out you can simply see the red barn with the white roof:
so, if someone sees some whiteish reflection in these building windows, it is very likely that they simply see the white roofs of the barns across the green or behind Trump…