How many miles before a shop is still liable for torquing the crank bolt? Mine fell out after maybe 8k miles? This was back in 2014 so way in the past, now. But at the time, it was a shop in SoCal that did my timing belt/water pump before my move to TN, so I had the cross-county drive plus however many miles added living in TN. When the bolt fell out I called my old shop and they pretty much offered zip as far as help with getting it fixed. Being several states away posed a problem, I get that. But they said it had been long enough it wasn't really on them anymore (if I recall correctly)
That all being said, when mine fell out, same thing, no warning. Just a weird noise (sounded like the torque converter failing at the time), a shudder, and the dash lit up. But the balancer fell clean off and caught on the sway bar. I drove the 20ish miles home on battery power and no power steering. When I finally found a guy to fix it, he used the updated bolt, a new HB, and I've put thousands more miles on the engine since then with no issues.
*Note- I'd had one shop try to fix it and they failed. Bolt fell right back out (they refunded me). When the guy who finally fixed it went in, he pulled out 2 quarter-inch pieces of bolt, one from the original bolt and one from the shop that failed to fix it. I had also tried to fix it myself as I could thread the bolt in without taking anything apart, but not realizing there were pieces of bolt still in there, I couldn't get the new bolt to torque, which seems to be why the first shop failed, too.