Most likely Disney will allow snack credits to be used for non-alcoholic foods and beverages as they have in past years. You cannot use TS or CS credits at the kiosks or for any of the special dining events so the Disney F&W page says dining plans are not accepted.
It is not a mistake. With the single exception of snack credits at the F&W kiosks in World Showcase. dining credits are not accepted for any Festival offierings. For some reason they don't seem to consider consider snack credit acceptance to count, but you cannot use any of your meal credits to get festival items.