They should transfer fine, just like copying any file from one computer to another, but you need to make sure that you are putting them in the correct location.
There is more than one Library\Preferences folder on a Mac, and the files must be placed in the preferences folder for the currently logged on user at the time the game is launched in order for VV3 to find them. For example, if you are logged on to your Mac as brady.gower, the savegame folder will be brady.gower\Library\Preferences\LDW\Virtual Villagers - The Secret City.
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Barbara
Unicorn
Last Day of Work