Starting in Vectorworks 2018, users can now create menu commands defined by Marionette networks.
To do this, select a wrapper in your file, right click, and choose "Convert to Menu Command..."
This will open a dialog window where you can name this command. A background process will save your Menu Command to a file in your User Folder.
Once that's complete, you can access the menu command by navigating to Tools > Marionette Commands > [YOUR COMMAND HERE]
This node when converted to a Menu command will scale the selected poly to a target area of your choice.
This menu command will take into account your primary unit settings. Feet & inches will scale by sq feet, inches will scale by sq inches, etc.
It works on selected objects and will prompt you for an area (but does not define which units in the dialog)