Regexps are an overkill in this case since emacs has a built-in command
transpose-words that is bound to
M-t by default. This command, combined with isearch are enough to solve the problem when linked together with emacs keyboard macros.
Learn to use keyboard macros and you can solve most repetative text editing tasks.
Place the cursor before the first line, start recording the keyboard macro, press
- to move the cursor to the next hyphen, press
M-t to transpose the words, stop recording. Then repeat the macro as many times as needed. Alternatively, you can apply the macro to a region of lines.