There is one unusual thing about "Spelling Options". I encountered one word that was misspelled and clicked "Learn" and the red line underneath disappeared.
I exited the "Spelling Options" and again invoked Spelling Options - it jumps to that same word but the word is now NOT underscored. The word is in the Mac English spelling database "en" . The same thing happens after closing the document and quitting AFPUB, then reopening the same document - jumps to that same (not underscored) word. In fact, if you happen to delete the misspelled word (I added a test word "asdfg"), the Spelling Options again jumps to this non-existent word in the text frame where it was originally found (but not after closing and reopening the document).
I would think AFPUB should not do any of that and just simply inform the user that there are no misspelled words to be found.
If there are no misspelled words, the Spelling Options dialogue just sits there quietly doing nothing. Not very informative.