Public transport (i.e. bus/train/metro routes and time schedules) is not supported on yournavigation.org. The option ‘public service’ is just for routing over ways that allow public service. In OSM mapping speak these are the ways that are labelled: psv=* (and probably emergency=*, but I’m not sure at this moment).
The Gosmore routing engine only performs least-cost routing based on road speeds for each type of transport. It doesn’t support public transport routes or time schedules. Perhaps it’s possible to pre-process the data to make Gosmore work ‘sort-of’ but it will never be good at it. You’d better find a different routing engine that is specifically built to handle this type of transport.