Hi,
This is the forum for the Revit API, this post would recieve quicker responce in the "Revit Architecture Forum".
Some info already,
Calculating percentages should be possible, but depending the source elements (count vs Area for example) you are going to need various additional columns. I can't exactly figure out what you want (maybe post a sample of desired outcome?)
One thing of note, the calculations will fail if elements that are included in the schedule don't have a value (wasn't set)
For example Yes/No tickboxes have 3 modes: Yes, No and No value, that last one will leave calculation results blank.
- Michel