I don’t think that “unisex” is unclear in OSM; it’s just confusing that it means something different to what “unisex” normally means in English and not what is meant here. If someone wants to start tagging this with some other tagging I’d happily render it on https://map.atownsend.org.uk/maps/map/map.html#zoom=19&lat=53.958126&lon=-1.09396 (that’s an example with “M” and “W” for separate male and female).