FYI & FWIW
I was having the same problems with installed programs not showing up.
When I looked, the redirects for CHS and SC were:
Neither has ever resided there.
FARR's path, however, was correctly identified.
Installing the 'available for installation' but already installed CHS and SC didn't help. They kept reappearing as available for installation.
Dragging the CHS and SC folders onto DCU didn't help, nor did dragging the relevant .dcupdate files to DCU.
Changing the paths in the .dcupdateredirect files in
C:\Documents and Settings\All Users\Application Data\DonationCoder\DcUpdater\RedirectFiles
sorted it out nicely.
I, too, think DCU is an excellent idea. The occasional quirk is only to be expected.
I thought that even I had made a mistake once upon a time... but then I discovered that was wrong.