Velocity did the brakes but not the brake fins which have been the issue. As for the launch, it has been operating at 99% since opening day this year. RMC is at fault here for the brake fins and sensing as well as issues with the trains.
Which set of brakes are you referring to? I know that braking fins were retrofitted onto the trains for DYNA-brakes that were added to the launch track in the event of a rollback. That said, the final brake run does NOT use these fins, they are only used in a rollback situation. The actual brake run uses a similar setup to the launch, which has been confirmed to be made by Velocity in the initial interview before LR was even built.
The pop up brake fins seem to be the issue not the actual magnetics.