If you are only changing the inside reveal depth field, then that will only modify the beam solar radiation absorbed and reflected by inside reveal surfaces -- horizontal surfaces between the inside face of the window and inside face of the wall.
If you read the Input Output Section on window reveal dimensions, this sentence about outside reveals explains why the window outside face sunlit fraction output variable is also not affected:
The outside reveal surfaces (top, bottom, left, right) have the same solar absorptance and depth. This depth is not input here but is automatically determined by the program — from window and wall vertices – as the distance between the plane of the outside face of the glazing and plane of the outside face of the parent wall.
In other words, the X-Y-Z coordinates of walls and windows would have to define the outside reveal -- your window surface would be drawn slightly "inward" toward the zone compared to the wall surface it is inside of. If they are in the same plane, which is how they are normally drawn, then there is no outside reveal. You can read more in this Unmet Hours post that mentions problems with trying to do this in the SketchUp plug-in (aka Euclid), and this OpenStudio tutorial where OpenStudio takes outside reveal depth as an input and alters the window surface location accordingly.
