I started spawn walking at Schwelm station. When the train 422 arrives can't enter its coaches. Tried another one just after that and had the same issue.
After a few days I tried again to enter the coaches from the same station and this time I succedded. It sims that you must find certain angle and than the popup button becomes available (E). Than I succesfully boarded that train. So you can not just walk in the coaches?
You want to board the locomotive or a coach of an AI driven train? I think there is no problem in just entering a coach when the doors open. For the locomotive you usually have to first open the door with E and depending on the loco aim for stairs/steps and press E again (climb in)
I think you mean Scwhelm station. According to the station route maps, it is definitely "Scwhelm" station..... https://forums.dovetailgames.com/threads/realism-and-other-topics-about-tsw.22576/#post-132953