Again, there's no evidence that Barriss is a darksider. From her perspective, it's the Order that turned away from the light. We must be careful not to define "evil" as "anyone who disagrees with our interpretation of things". Barriss simply had a different interpretation of where light and dark were located in the last days of the Clone Wars than the Order did. Considering how events unfolded in the months afterwards, can we really say with any confidence that her interpretation was any worse than theirs?