This may get a little deep, but I want to document the details here.

1. Based on a quick inspection of the source code, it appears that the surface inside face temperature (TempSurfIn) for a window is the temperature of the inside face of the glazing. This variable is used for meant radiant temperature and operative temperature calculations (wrong for a shaded window).

2. A separate effective surface temperature is calculated for shaded windows (EffInsSurfTemp) which is defined as "Effective inside surface temperature for window with interior blind or shade; combination of shade/blind and glass temperatures." This temperature is used for interior radiant exchange (correct).

3. For the equivalent layer window model (Construction:WindowEquivalentLayer) EffInsSurfTemp = TempSurfIn, so you may see the impact you expect if you use the equivalent layer window model.