I would like for ArchiCAD composite walls to clean up when skins of matching fill touch, even if reference lines do not touch.
Very often, in multi-way junctions at corners, reference lines cannot be flipped to accommodate a junction with one wall without breaking the junction with another wall on the opposite side - forcing messy workarounds such as breaking walls up into little segments.
Healing between identical fills that are touching should be the default behaviour irrespective of reference line position. On those rare occasions when not required, user can leave a small gap.
Reference lines for walls generally I suspect have outlived their usefulness - they necessitate too much trial & error & juggling at intersections, and otherwise confer little benefit (except to the programmers) that I can see.