I have taken mine on the train before and they seemed fine, they were actually more chilled than in a car, I think because the motion is smoother and less twisty. They were even eating and napping en route!
However I did choose a route and time that I knew would be super quiet, they got a seat to themselves and there was pretty much no one else in the carriage. I don't know if it's practical for you but maybe if you can pick a super quiet time that would help...?