Is there a way to fill the contents of the 'enumeration datatype' or the 'transformation menu' by importing from a file?

Background:
So there is the requirement to present the user who is entering code in the projectional editor, with a pop-up view of contextual choices.
The pop-up view is something like the (preferable) 'enumeration datatype' or the 'transformation menu'.
The choices consist of a list of functional data items which hides the technical (xpath) data items. The context is the kind of xml-messagetype. So the presented choices should be context aware in that it is depended on the kind of xml-message.
Because we have a lot of xml-messagetypes and each xml-messagetype consists of a lot of data items, I like to have an simple automated process to assemble an 'enumeration datatype' or the 'transformation menu' from an imported data file. But how?

I've read the "Custom Persistence Cookbook" that is mentioned in the post "Is it possible to bring a file's content (Say the file has a list of options) into auto completion menu?", but the implementation is rather difficult for a designer. Maybe in the last 4 years some progress have been made in the MPS workbench to address this requirement?
Maybe there are other solutions for my requirement? Or maybe an xsd can be imported into the workbench?

Like to hear from the community,
Regards, Djon.