Yeah I have tagged half a dozen or more Ulsterbus routes that now operate from Grand Central Station - Translink's own app (which uses OSM mapping!) is a dog's dinner at that area, their routing algorithm is all over the place.  One tagging decision I made was to simply show all the busses using one 'bus stop', rather than to try and tag them on particular bus stands (as in my experience these change frequently, as drivers don't always pull up in the right stand anyways!)  