I came across a problem with the SCH files. If you copy them to a new directory and include them in a project as a sub sch KiCAD creates extra records for each about, an “AR”. These have a field with a ? in it and seemingly do nothing, they may have a use but I don’t know what it is.
This was just an announce till yesterday when a sch stopped loading because of it. I’ve written a small utility very badly to tidy the files up. It is on git hub if anyone wants it.