According to
https://forums.dovetailgames.com/threads/tsw-update-notes.15077/, the following has been fixed, mainly because some of those German trains are now interoperable between the new route and Ruhr Sieg Nord, the game is now at build 551:
22nd of February 2019:
An update following the PC launch of Main Spessart Bahn to address issues identified by the community.
DB DoppelStockwagen Control Car
- Fixed passenger Door Selector switch not allowing doors to be locked when in the "Unlock All/Both" position
DB BR 143
- Fixed a bug which prevented the BR 143 from opening passenger doors when swapped in as an AI train, resulting in service mode coming to a stop with blocked trains behind any 143s.
Route
- Fixed a missing scenario start marker for the "Doppelstock Delivery" scenario when exploring Gemünden in Service Mode.
- Fixed various collision boundary issues.
DB BR 146.2
- Fixed an issue where the BR 146.2 from the Main-Spessart Bahn route incorrectly presented as available for Freight duties on Ruhr-Sieg Nord route.
-------------------------
Still no word on the promised US Diesel physics update, but since the USA should be next in line for a new DLC, perhaps the update to CSX:HH and NEC:NYC and GP40 pack will come with that new DLC.