There are actually 2 different paths here, which in certain cases coincide, depending on how exactly the model was created.
One is the location in the model repository explorer (see right-click > Show in Repository Explorer, as well as the id property shown in the Properties view). To retrieve this programmatically pass a reference to the element to Miscellaneous/Get Model/<Instance> which returns a Model structure containing the Model Id.
The other is the location of the model instance (or element) in a specific view (models can be reused). To retrieve this pro grammatically, you'll need to create a process which retrieves the path recursively, by getting the parent element, and that parent's parent and so on. Use Display Actions/Get Parent to retreive a given element's parent followed by Display Actions/Get Element Name to retrieve the element's name, and do so recursively until Get Parent returns nothing, which indicates you have reached the view level.
Both methods outlined above apply to display elements, only, which seem to be what you're attempting to do in the first place.
Doing the same for non-display models is not supported - references to processes is not (yet?) supported, and we're still looking for a good reason to implement such a thing.
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