I think the "will they/won't they conquer their fears" thing is or was compelling, certainly ten-twenty years ago when it hadn't really been done on television before, and certainly it was the sort of thing I found very interesting to watch whilst growing up - certainly mainland Europe beat us Brits to it (Fort Boyard's been playing Indiana Jones for twenty years now and still going, Now or Never would have been what, mid 90s? (although the episode I've got is a bit gentler than your pilot, by the sounds of it), Il Grande Giochi/El Gran Juego de Oca again early-mid 90s). Then I'm a Celebrity Get Me Out of Here became a massive hit, thanks to a) Ant and Dec and b) the Bushtucker Trials.
These days it's much less of a draw, because surely everything's been done by now? Fort Boyard has been struggling to come up with anything interesting for its adventures the last few years (but at least has a strong non-fear based element as well), and I can't help but think coming up with new Bushtucker Trials year on year must be one of the hardest jobs in the world to do. Ratings are down across the board. Both of these shows are hindered (although in other ways it's also their strength I should add) by their location and format, Fear Factor's genius, if you like, is that it had creative freedom to dress its tasks up anyway they like to keep it interesting. Ditto Japan's legendary Za Gaman (Endurance), which also had slightly more nuance to it than clip shows would suggest.
ITV recently did a show called The Door, hosted by Chris Tarrant and Amanda Holden. They were trying to promote it as "the new Crystal Maze". It really wasn't, it was two hours of celebrities trying to find things in containers full of awfulness. I might have found it entertaining if I was 15 and hadn't seen the like before, but I'm not, I have and it largely wasn't.
I think what Panic Attack needs is twenty years or so where nothing similar has been on since. Failing that, it's going to need a lot of compelling scenarios - never lose sight of the fact there is entertainment in watching others do things you would not and could not do.