not finding the file because it's searching the wrong place is indeed a special case of "something goes wrong when the code attempts to open the chd" :P

the problem is the last NULL parameter of the open_disk_image call at line 486, which is the "locationtag" that it is used properly when you load from softlist
it shall be in the format "swlist % clonename % parentname" to allow the various places to be properly scanned

as is audit_one_disk has no way to retrieve the proper locationtag, and hence there is no easy way to fix this. I will see if I have any smart idea for a solution, or if Micko or you or anyone else beats me to it...