There was an interesting bit at the end of the last road map stream where Matt P mentioned he was being nagged by one of the community team who had a hitlist of the top 10 issues raised on these forums. This de-railing issue must be on that list. Reported constantly by multiple people, even acknowledged by dtg. Now these might be considered minor issues / low priority in the grand scheme of things, but surely, the number of complaints about this issue warrants an urgent fix. The same with the Dresden tutorial.
I had documented a possible workaround in the thread below. By the time it was recorded on PS4 & TSW2. I wouldn´t know if this works on other platforms and in TSW3. But you might give it a shot (if you´re able to enter the loco in time, that is). At least it would complete the chapter. For Completionists: Workaround For 5x03 Coach Preparation
Completely agree with you. Having a journey mode that is not able to be finished should be high priority, same with issues with tutorials and collectibles. DTG could reduce by half the number of posts in these technical forums, just by addressing a small number of very long-standing issues