To me, "return" implies a "go back" action (like "backspace"), which is the opposite of "enter", so naming the key the latter makes more sense. Plenty of TUIs used the arrow keys, Backspace, and Enter for navigation.
Also, the text is nicely readable but none of the images are viewable.
As I understand it, "return" is a shorthand for "carriage return" - as on typewriters, going to a new line meant returning the carriage to its original (start of line) position.
You’re “returning” whatever text you typed to the program accepting input.
It was one of the things I found amusing my first time using OS X after growing up on Windows. Enter would “enter” a folder or execute a program, while Return in Finder starts renaming the file.