When I first tried CyberDuck, i was delighted to see those two commands:Synchronize and keep filestamps.
But it does not work at all with OpenStack (Public Cloud storage with OVH).
Hence it is impossible to synchronize computers. If you upload a file with CyberDuck or MountainDuck, you will download this very file on the other computers even if the file has not been modified.
As long as it won't be in use, I won't buy a MountainDuck license.
I am sure it's a CyberDuck and MountainDuck problem, because it does not happen when I upload manually a file or using rClone or rClone browser.
If you do not plan to fix this, you should erase those two commands.
OpenStack Swift does not support setting timestamps for files but will always report the server side modification date. We could add a custom property to metadata but this is not feasible for performance reasons as querying the metadata requires another request for every single file in the object listing.