Ah, I didn't think about backwards compatibility. Thank you for pointing that out and your other suggestions.
Looking at the original predefines, I've realized they're the basic RGB/CMYK+white&transparent. Considering this and the ideology of SFML, it seems to me that additional color predefines is unnecessary and antithetical.
But, it would be nice to have HTML colors ready at one's fingertips, so I've implemented your
HtmlColors suggestion. My refactored text can be found
here. Just stick it somewhere in your project or include it in your personal SFML build if you wish.