Many thanks for your time and effort; they're much appreciated.
My first reaction was astonishment that
you, of all people, directed me to
CNET, of all places, but after seeing that the only spellchecker offered by the App Store
and MacUpdate combined that's been updated since 2010 is by AplhaOmega, the biggest thieves on the Internet, I recognized a possible "why".
Unfortunately, though, CNET's offerings fall into the same developmental range, i.e. the last time one of them was updated was in 2010.
I guess I'm stuck with what Apple has given me until until either they respond positively to my feedback or a third party developer feels the same way I do.