The site seems far too small to be much of a “resting place” for WWI Italian soldiers. It does not seem large enough to hold what seems to me to be as many folks as it likely took to build the place. Would so many build such a difficult site that a bare few could enjoy? I don’t think so.
I can see one WWI advantage the site had - possible strategic observations. But to achieve that advantage would require communicating the observations. Radio contact would of course been the best way to do that, but it’s a question whether the occupants had the means for that. Without radio contact, observers at the site would have to climb back out of the site and hike and travel to somewhere else to communicate their observations.
Therefore I question the WWI hypothesis.
Maybe it was built by some, a few, AWOL soldiers as a hiding place until hostilities were over. One or two at a time could sneak back and forth to family and friends, to refresh their supplies, and given their location likely remained undiscovered as long as the fighting went on.
Reply #50 may change your view?