Modification (?) dates don’t match after sync

I just synced my iPad and Mac.

The same file has a date of 4 Jul 2017 02:09 in the Scrivener for iOS project icons and a date of 7:22 AM today in the Mac Finder. I have definitely opened the file since July of last year, but I didn’t open it this morning.

Another has a date in iOS of 4 May 2018 13:36, and in MacOS of 5 May 2018 at 3:11 PM.

What do the dates in iOS actually mean? It seems they cannot be relied upon to indicate when the project was last modified.

No, they can’t because what you see is different things. First, what you see is a folder, not a file. Secondly, the dates relate to what happened on the HD you are looking at and if you sync your Mac the date reflects that. If you look at the DB server it reflects when something happened there, and the same on your iOS device.