I feel like she approached from the Spanish side for the simple reason she didn’t make anymore cell communications, and her own SMS messages seemed to indicate that was what she might be doing.
That said, I still don’t get how she could fall going to the X on the previous images. Looking at the contours and the steepness of the grass in the previous photo it seems any slip would have caused her to slip back down towards the lake, not over the ridge into France. The only thing that explains that (again, just by looking at Google earth) is if she physically walked over the top ridge onto the other side, which doesn’t seem likely to me. If she was further away from the port, towards the actually pic, a fall here seems like she could possibly end up on the France side. But from the X I can’t personally see it (am I wrong here, can a person slip at that point from the Spanish side and slide down onto the other side?), not without careless stepping onto the other side or getting blown over.