I guess you are using fills to show a wall finish and want to schedule the surface area.
There are other options to extract these by using zones. Since you can update zones automatically, you don't have to manually adjust fills anymore, so it might work out better for you.
The type of schedule you want to make for this is 'Elements', set it up for Element Type Zone and preferably filter it by layer to only use the zones you want to schedule. For fields the one that is needed is 'walls surface area' from the zone category.
From there on I would add some custom properties for the zone to list the wall finishes and have an extra option.
If you have multiple different wall finishes, you will need a different approach.
For this you can use actual Surfaces in Archicad to show the correct finish on the walls and create a Surfaces schedule where you show Exposed Area (by criteria). Under the criteria of this you can filter which elements should be calculated.
For a schedule like this I would expand the criteria to filter out most of the model by using layers, elements (walls, columns, beams), building materials (hide things like 'air' or insulation), possibly a short list of the surfaces and related zone categories. I suggest this or it will be a very long schedule, showing many things you don't want to see and it will take longer to generate.
Hope this helps a bit. It is unlikely the wish will be granted soon!