IMO a solution of this general nature is the only way we're likely to move forward WRT things that are too ambiguous to reliably handle with TWYS.

However, to my mind the most pressing problem is not the precise choice of protocol, but how to get people to adopt it. One idea on that front is for support to be incorporated into a userscript like E6Extend. Something like, when editing, 'Split the Description field on the string Lore_tags:\n, place the first result of this into the Description field. Place the second result of this into a new "Lore tags" field. When submitting, combine these two fields to reverse the process'