Now the boons description says it only hurts it foes but its effects seem to take action against creatures in general.
Now does this mean if a group uses barrier to make a fog dome to mask themselves would they also be blinded by the boon since they wouldn’t be able to see through it? or would enemies only be unable to see through it?
The description sections are just to help you understand what the ability represents, they don’t actually have any rules meaning. The description of Barrier is assuming that you would almost always want to use it on your enemies rather than your allies. For balance reasons, Barrier works on everyone unless special rules or circumstances say otherwise.
The example of the fog dome is even more clear cut; if the Barrier is representing a fog cloud then of course the group also can’t see through it. Common sense always applies while you’re playing, so unless your character has an ability which would let them see through fog they simply can’t.