(regarding the idea of adding forced pathing)
I would suggest a mode where you can set each train's exact location and also its schedule (Go here, then here, then here), and then hit play, so you can watch what route it tries to take automatically, and also experiment to see what causes collisions.
I have an urge to make an inspired-by game, (so I could add touch screen and play on my phone), and I would add S-bends so you can send a train down a parallel track 1 or 2 squares over instead of minimum 3 squares over. But I feel that it would be a different game. The inefficiencies are part of the puzzle. Leaning into that, I would also add trains getting multiple train cars.