One of hte problems iwht thet train scenario is that it is complicated for hte defender, and many players never get much skill at defending - ther is no incentive the get on the train.
Sure itwill help with a win, nut I’ve only seen hte train defeated once so far, so that seems unlikely to many. Many players get on the train, halt it, then immediately get off because kills are more important and give an immediate reward - halting the train does not.
So i suggest an incentive for defenders to get on the train - nothing major - somthing like +10 score for every 30 seconds on the train - but only WHEN IT IS HALTED.