I guess we either trust in the whole warscroll or none of it.
It weren't the skills that needed boost but stats. What good comes from them moving around tge battlefield if they are close to useless in combat? Poor save, 1 wound, 4 to hit. I don't buy their function as moving walls. They should be a commando unit. Fragile but deadly. If they weren't needed for Gnarlwood I would never take them for the fight.