I've only flown night missions in the "M" version of the Gazelle. The NVGs are already on the helmet and all you have to do is hit the key command for NVGs. Then you are looking through them.
I'm assuming you are talking about the "L" version? Pilots don't have goggles attached to helmets in that version. I've never tried night flying in the "L" version.
My start of this thread was because something changed, that being when you utilized your NVGs then let's say switched over to the other pilot and looked back at the other seat you were piloting from, the NVGs animation were down over the eyes. It looked like those pilots were indeed seeing through those goggles. Now that doesn't or didn't work. Have check lately whether that has been fixed.