In ARCHICAD 19 and older: You can Override Fills in the Model View Options Dialog to transparent so there will not be any Fills (so they will all be uniform). Also, you can create a Pen Set only for the Schedule in which all those different Pens are the same color. Then you save a View of the Schedule using these settings so you can restore this state anytime later.
In ARCHICAD 20: I think you will be able to simply override the Pen Color, Pen Thickness, Fill Type, Fill Foreground/Background Color, Surface of all elements in these model-generated Schedule cells using the new Graphic Overrides feature.
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