What is the name for this curved arrow formatting symbol that displays when Shift + Enter is used? Is it correct to refer to Shift + Enter as a soft return?
The symbol has the Unicode name "Downwards Arrow With Corner Leftwards" <whew!> and the character code 21B5 (hex). As far as I know, nobody refers to it that way.
The function in Word represented by that symbol is the "manual line break". I think the only place in the program where you'll see that name is on the Special popup in the Find and Replace dialog.
Word has never used the "soft" and "hard" terminology, probably because WordPerfect did use it. (MS used to consider WP its mortal enemy.)