Exception in case of spelling error

How do I detect in a grammar or disambiguation rule that a word is not in the speller dictionary?

I think that’s not possible. What is your use case?

I am detecting words that are not expected in between the surrounding tokens. I can make exceptions for word types that are common in between the words, leaving the uncommon for a message. But sometimes, it is correct word, of an allowed type, just not in the tagger. I can use UNKNOWN to filter those out.
But even then it leaves the words that are succesfully tagged in the disambiguator.
In those cases, the rule show a ‘possible spelling error’ as well as a hit on this ‘uncommon word order’ rule.