In the current wording of the rules, it says "If miniatures in the defending unit are obscured by terrain that provides light cover and some terrain that provides heavy cover, if more than half of the obscured miniatures are obscured by terrain that provides heavy cover, the defending unit has heavy cover."
If there is any unit with an even number of minis, if half are in heavy cover and half are in no cover, the unit has heavy cover. However, with this wording, if half of the unit is in heavy cover and half is in light cover, the unit has light cover. Is this intentional?