It does seem to be the case for linked charts, I've made a test document with two sheets with the two linked charts on them and in the expression overview there is now no longer a sheet name. (Attached DateTest.qvw)
As to your problem of finding objects and or expressions, you could xml read your qvw file. In the load script editor use the table files wizard, point to your qvw document and open and in the next step set the file type to xml.
I made an example loading the first example with a table showing the SheetID, OBjectID and definition (with expression).
Now both are shown.