Well, if you start the service 50244 on SKW (or even better in journey mode) the timetable tells you... 23:13 at Langenschwarz... well, I tried hard, but failed...actually, even when spawning on foot in Langenschwarz...well, at 23:13 no AI 50244 in sight...so,I waited and well... finally it arrived...the AI train with 14 minutes behind schedule (not taking the bad weather in journey mode in account)...well, I somehow lost my passion to wait for the train in KS-Wilhelmshöhe, but, I guess, 00:12 wouldn't even be doable by the AI train...
This scenario/timetable is broken for me as well as of TSW6. Game makes you wait just after Fulda station while another train passes. There's no way to make Langenschwarz at the given time, and I'm not even sure you could do it with that passing train removed.
Well, I tried it in free roam with an ICE 1 (BR 401) and yes, I made it to Langenschwarz (somewhat around 23:13:30) in time, seems like they messed up timings for freight trains with timings for an ICE...^^
More discussion on the subject here. This journey/scenario/timetable is duplicated twice now in TSW6's journey mode for me, one that is completely dry like in OP, and one that is very cold/snowy. I think you were doing better than me on timing - the earliest I could make it to the end was 00:47. A fair amount of waiting at signals, but still a fun and challenging mission. Just wish the timetable its self was more accurate.
That's funny... It would be interesting to have the same mission doing a passenger service as well as the freight. Hope they come back to this addon to fix. Edit: Is it possible to make a modification for the timetable/mission?