Please alight the bus through the read door = Please exit the bus/ get off the bus through the rear door.
Alight is rarely used in the US. It’s used more commonly in previous British Colonies because of the Brit. influence.
Disembark is more of formal usage, typically used in reference to ocean liners and long distant trains.
You won’t hear “disembarkation” on a daily commute train however.
He got down from the train- is just totally sounding odd. Everybody is getting down - sounds like something you would say when everyone is having a good time in a party…..![Smile [:)]](/emoticons/emotion-1.gif)