Order System Meta Fields have a slight difference in their creation in 5.0 and 5.2. All subelements are equivalent except for the Namespace element. When an Order System Meta Field is created in 5.0, its associated namespace value is "Mediachase.Commerce.Orders.System". See the export snippet below.
When an Order System Meta Field is created in 5.0 its associated namespace value is "Mediachase.Commerce.Orders". See the export snippet below.
The xml configuration file that drives the "Meta Fields" view can be found here:
The ascx control that is referenced in the above file can be found here:
As an aside, the above control uses a querystring key "FieldNamespace" to get a string value that is the namespace of the meta fields to be displayed in the "Meta Fields" view. You can modify the value from "Mediachase.Commerce.Orders" to "Mediachase.Commerce.Orders.System" to test this. Below is a before and after example url with the fieldnamespace query string changed on a sample implementation http://localhost.ecfcamerademo. You can try this out on your local installation and view the different meta field records that are displayed.