For the feature’s official web presence, yes. Please don’t use it for other URLs - that was the point of splitting the old url=* key into website=, wikipedia=, image=* etc. in the first place! But of course you can invent your own key.

However, I think the actual issue is the software anyway. Maybe you could have a look at Wikipedia’s solution for their OSM integration? They place a linked marker for every article with a coordinate on top of an OSM map. Alternatively, maybe you could use some ideas from OpenLinkMap? Both don’t use areas’ outlines, unfortunately, only markers.