I know right now there is list of all BCS multiplayer supported maps: https://busbetrieb-simulator.de/maps.php?lang=en
However I think we actually need an improved list that lists all supported maps with the version number and additionally show for each map which addons have been added to them and even preferably links to where to get them.
Ahlheim Laurenzbach [v1] - No link available
| - Viele neue Fahrpläne für verschiedene Maps (Ahlheim & Laurenzbach) LINK
| - Nachtlinien für Ahlheim-Laurenzbach LINK
Fikcyjny Szczecin [v2.50.03] LINK
If not anything else than maybe a proper thread in the forums somewhere or something like that.