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.
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.
Doesn't seem perfectly consistent in English either. When there is a "wagon train" in a Western movie it is often full of people in wagons. Seems like wagon vs carriage is a bit more complex than just if it carries people or not?