B&M Hyper Coaster Question

My understanding as well is that the bars have to be down at least two latching points. Meaning all four latch paws would have to fail twice (once on the first latching point, then skip to the next latching point and fail again).

That is why they had the "red" line painted on the bottom of the restraints. The red line indicated when the restraint was down at least two notches.

The seat belt on inverted coasters did the same thing, it was a measuring device making sure the bar was down at least two latching points.

In the modern coasters there is an electronic indicator to make sure of this so the red lines are no longer required. But that is the reason why pulling up on the restraints was not a valid check, because the bars could be resting only on the first latching point.

^All B&M Hypers from the very beginning have had the sensors for the restraint. The red (or other color depending on the specific ride) line is simply an estimation to give the attendant an idea of whether he/she should try to get the restraint down further. That saves some time compared to having to return to the seat after checking the whole train when the operator calls out "check 2".