There are no spellcheck feature because almost all browsers already has built-in spellchecker.
In fact, the spellcheck features on website usually interfere with browser's spellcheck and causes more problems.
I know this thread says, "resolved", but my spellcheck and grammar-check seem erratic on this new platform. It's not a big issue but I feel a wee bit undressed.
Perhaps you could try another spellcheck? You could start a thread in Site Help and ask people which ones are working for them here. Be sure to tell them what browser you use.