The AoA sensor is another shitstorm, hardware failure plus its undocumented relative calibration problem:
"...the output from Resolver 2 was correct when the internal heaters were operating but stopped working again when the temperature dropped.
The investigation discovered that a loose loop of the very fine magnet wire from the primary rotor coil was trapped in the epoxy which was meant to hold the end cap insulator in place. The trapped magnet wire thus adhered to both the end cap insulator and the rotor shaft insulator which had very different coefficients of thermal expansion (CTE). As the wire expanded and contracted to the two different environments, the wire became fatigued and showed multiple ridges and cracks before breaking. The wire failure created an intermittent open circuit, dependent on temperature. The sensor worked fine at temperatures above 60°C (140°F) but failed at temperatures below that."
https://fearoflanding.com/accidents/accident-reports/lion-air-610-the-faulty-aoa-sensor/
I'm not sure what you mean by undocumented relative calibration problem. This was a problem, but it was a documented and allowed procedure that was used. The calibration issue was due to the remanufacturer using a nonstandard piece of test equipment and associated nonstandard procedure, with the approval of the FAA, which included this mode that was not part of the recommended test equipment. This procedure was documented and approved, it just failed to correctly deal with the setting of this REL switch. As this wasn't a recommended procedure, I don't think you can blame Boeing or the AOA vane subcontractor for that.
Yeah, the initial failure that triggered replacement with the miscalibrated sensor is certainly interesting, but it definitely doesn't strike me as a shitstorm. Possibly a QA issue, possibly just an unexpected consequence of the manufacturing process, should be easy to fix going forward and isn't obviously a result of malice. It's not made or designed by Boeing, and I haven't seen anything implicating the sort of management problems at Boeing at their subcontractors (yes, Collins failed to catch the AOA DISAGREE alert issue, as did Boeing, but they were then ordered not to fix the problem because
??). These kind of manufacturing issues always come up with new aircraft in one system or another, get resolved, and because the designs are usually proper, don't result in crashes. Aircraft are incredibly complicated, and to expect no issues at all of this type isn't reasonable, which is why the engineering needs to account for occasional failures.
Indeed, what actually happened in this case - the problem was detected by the flight computers, the plane flew several legs safely (probably should have been grounded earlier, yet...), eventually the problem was isolated, and the part replaced - is what one would expect to happen. In fact, if I understand the fault correctly, I don't think it would be likely for this original failure to trigger MCAS at all, an open circuit is an outright failure that would be detected, and the sensor was otherwise providing correct readings. Ultimately (bar MCAS), the AOA vane is a non-critical and 'fault tolerant' system on the 737 - I can't easily find if the 737NG and 737MAX use the same AOA sensor part; I would guess that they do or one of very similar design, and NG has been flying in the 1000s without AOA vanes contributing to an accident for 20 years.
Even if you're right and this is a complete disaster of an AOA sensor design or manufacture for some reason, failure still shouldn't have had any effect on safety of flight, even complete loss of AOA data isn't an issue for any 737 (which is why it's only doubly redundant), so I think this is just an interesting footnote to the story. If the design of the system on the Boeing side wasn't such a clusterfuck, the inconsistent readings would be detected, trigger a disagree, and the faulty data wouldn't be used for anything.