Read what John Ellis said in that thread. Seems to apply here.
You need to understand the different types of dates before you go any further. The file creation date may NOT have anything to do with the "capture time" Lr uses, which itself is usually derived from the exif date created.
Lr and other photo applications rarely, if ever, mess with the Mac Finder file creation date. It's apples and oranges. But backup software, copying, cloning, disk problems, and other stuff can mess it up.
The command line program touch is the way to go here and will set the creation date to anything you like.
If you don't like using Terminal, however, then seek out File Date Changer or maybe the more comprehensive File Multi Tool in the Mac App Store (from the A Better Rename folks). It can change the file creation dates, and do lots of other nifty stuff. Some other utilities might as well; my copy of MacPilot can change one, but not batches.
thank you! the File Multi Tool solved the issue seamlessly, and i'm hoping that i don't encounter that issue again.
in another forum i saw that someone wrote that when the date changes to 12/31/69 it's usually because "the backup / clock battery in your workstation or laptop is no longer holding a charge." also, "Unplugging an external USB hard drive while your Mac is in sleep mode may reset the Date Modified settings of all the files on the external drive to December 31 1969."
i don't think i've done either of these, but i'm also realizing that my chronosync doesn't recognize "date created" changes unless it's a brand new sync script (which i created and ran after i renamed my drives), so it could have happened a while back without my knowledge.
thanks for your help!