I tried the new feature and I think it’s not working as expected:
If you modify the Modified date and close the panel the date you set will be written to Created date
If you highlight the year (on one of the two dates), type “20” and then stop for a second DT will “autocomplete” the year to 0020. If you now close the panel that year is written and shown in DT and even in PathFinder (but not in Finder). No check on year set by the user?
I also suspect (but not able to test) that you can set dates not congruent to each other (i.e. modification date earlier than creation date).
korm already explained to me that it’s intentional and dates in DT can be different from dates in the file system.
Since the meaning of that two properties is quite clear and doesn’t leave any space to imaginative interpretation I think that DT “creation date” and “modification date” should be kept aligned to the ones in file system and I cannot see any case in which a user can take advantage setting a different date.
I rebooted my system and the glitch persists.