Hi, thank you for creating a poll and looking into this! 
I also noticed that the addresses are on the service provider webpage. So, these data are publicly available, but I am unsure of their license.

Usually, the address of the station is that of the nearest, prominent building. What this building is, is usually also indicated in the name of the station.
Some stations do not have addresses specified neither on the webpage or in the app. See [10811367774](https://www.openstreetmap.org/node/10811367774#map=14/46.0436/14.5332) for an example.
If an address does exist, I don't think it is ever unique. After all, these are in essence just parking spaces, which normally don't have any addresses assigned.