Half >24-hour bump, half more info:
I don't think this will fix the problem, but just giving an update to what I've done and what I'm doing:
I verified that my USB hard drive is on the list of "working with the Wii" hard drives.
I have the hard drive attached to my computer and currently restoring the ISO images off of the WBFS-formatted hard drive so I can FAT32 format it and restore the .ISO files as .WBFS files that CFG ISO seems to be wanting.
When that's done, I'll test things to see how they work, but I'm not expecting this to magically make the games that are not working, work. I'm thinking there is something else wrong. Did anyone have any ideas?