Jarek 🚲
the transitway is actually mapped, for example https://www.openstreetmap.org/way/724771885

The BLUE line is mapped as https://www.openstreetmap.org/relation/12717111

Transitway is not rendered on default openstreetmap.org map because that map doesn't show highway=busway tag, but the data is correct. You can see the transit route by switching to "Transport Map" or "ÖPNVKarte" view in the Layers switcher