WordPress SEO (free) is dealing well with most special characters but in spanish, any question starts with a "¿" (Interrogation mark inverted)
It is not considered now as a special character in WordPress SEO which creates false positive in standard optimisation Tab
KEYWORD: Whatever comes here
¿Whatever comes here? --> Negative WPSEO stat (Correct editorial sequence)
Whatever comes here? --> Positive WPSEO stat (Incorrect editorial sequence)
It affects all SEO elements
It would be nice if you could correct that in the future.