In my opinion, OSM should have a relation structure that reflects on-the-ground reality as well as possible (even if it isn’t particularly usable because reasons), or else the structure can be a mere convenience for bookkeeping purposes.
At the same time, I also see value in the map data files on Wikimedia Commons, which are available to everyone on the Internet. By contrast, the API you’re relying on for Wikivoyage – the geoline service – is exclusive to Wikimedia wikis. External wikis like OSM’s aren’t allowed to use it, let alone consumer-facing applications. Synchronization is a problem, though it might be possible to develop a bot that periodically synchronizes the files based on some kind of marker or relation structure that we put directly in OSM.