it was such a surprise to find it still calibrated
Finding it within 10% isn't 'calibrated', probably more than twice it's tolerance out of spec.
In all the years I've been involved in calibration and torque calibration especially, I have never found a bendy bar one in spec after it's first calibration - bear in mind a lot of the users I know will calibrate them on a 3 month frequency. I honestly don't know anyone who uses them anywhere, in any company or in any country I've worked in.
They may well be ok for the odd job home mechanic, but in my experience I wouldn't use one.