Hi Bob,
Yes, thankfully the roll back process appears to have returned everything back to the way it was. My C:Users folder contains my original username folder and a couple of practically empty folders (Default.migrated and DefaultAppPool) - I can't remember if these were there before but they don't take up any space. The process was fully automatic and pretty fast. Google search with "roll back windows 10 1903" takes you straight there.
It's very frustrating and obvious that MS only caters for the apparent masses/default configurations when doing this type of upgrade. Anyone who's used their PC for some time and/or who has configured their system on even a slightly more advanced level is going to be very annoyed. For myself I do have a system upgrade pending - moving onto Zen2 from Intel, maybe 3950x or the new Threadripper (16 core only) for more PCIe lanes etc. I'll be reinstalling Windows 10 so I'd like to think 1903 or later will come with the MS download. Getting the latest W10 (with 1903 built in) and re-installing might be an option for you providing reinstalling and configuring all your current software and options isn't too much of a headache.