I experience that if I change the date on a picture in Lightroom CC, the change is not reflected in the local storage. I have to delete the local file for the image to get resync'ed in the correct date folder. Is this a bug in LR CC, or is this expected behavior?
Yes, that's correct. I tried it again now. Changing the date doesn't cause the image file to be synced to a folder with the new date. I have to delete the file locally for Lightroom CC to sync it again correctly. It also takes a very long time for Lightroom CC to figure out that the file is no longer present locally. So currently I don't feel the "download original" feature is very trustworthy. At least in the sense that the downloaded originals should be a backup of the cloud library.
I see now that the same goes for a bunch of video files that I corrected the date on a week or so ago. These files are still in the folder corresponding to the date that the videos had before I corrected them.