Why would wagon return make sense? I don’t see the connection. A carriage is something that holds things for transport. A wagon is specifically the wheeled thing that is pulled along. Typewriters aren’t wheeled transports.
A carriage is a wagon that transports people, not "things", a carriage are also usually wheeled, just like wagons.
In this case, one reason why "wagon return" might have made more sense is because there is a wagon that holds the platen of the typewriter.
Carriage is another word for wagon (german Wagen, swedish vagn)
It makes sense because it's the same word in Swedish, the distinction doesn't exist.