This it how it doesn’t work:
2 You select it
3 You right-click to get to the “learn spelling” menu. It is NOT there - BUG
4 You unselect the word and now you can go to the new character name and the “learn spelling” command is there.
Resolution needed: let “learn spelling” to be there when the new word is selected and you right-click.
Learn spelling is a built-in Mac function, not a Scrivener function.
Have you restarted your Mac?
“Learn spelling” works in Pages, Text Edit.
Only doesn’t work in Scrivener.
Bug has been acknowledged 2 years ago: [LH2738] "Learn Spelling" Issues
Workaround is go two layers into submenu spelling and grammar - show spelling and grammar. Then you have a window and there you can add the word to the dictionary.
4 steps instead of 1
It would be a good thing to finally fix that bug.
The thread you linked to refers to the Windows version, not the Mac version,