With respect, that is definitely not right.
Here's Defender:
* "Scores 1, 2, or 3 VP for having 1, 2, or 3 completed Wall sections. This means filling all the boxes
in each of the 3 sections (within the Small, Medium and Large Granaries)"
And here's Vanguard:
* "Scores 1, 2, or 3 VP for having 1, 2, or 3 completed Wall Guard sections. This means filling all
the boxes in each of the 3 sections (within the Small, Medium and Large Granaries)"
Notice that these are identical with only one difference -- one says "wall" and one says "wall guard." These two clearly refer to the two tracks, one titled "wall" and the other "wall guard". If Defender meant you have to fill in ALL the boxes on a third of the map and not just the "wall" boxes, then Vanguard would have to mean the same thing by the same logic, but obviously they can't both mean the same thing. The wall/wall guard distinction is the key to understanding their meaning.
In any case, that argument aside, what you describe is _definitely_ not how it's workin in the implementation, for example here
https://boardgamearena.com/11/hadriansw ... =480634832
It scores a point on Defender simply for having a third of the "fort" track filled in. But it should be scoring a point for having a third of the "wall" track filled in, per the wording on the card.