Without any pointing to the crew, which is hopefully recovering, we may discuss the playing field in which they had to operate and make decisions. Not to blame, but to learn from it.
All pilots have been in situations where they were "forced" to fly, and after many years concluded how in the world they'd accepted that then. But got away with it with luck. At least I had my share.
Initially I thought the flight was one of a series of flight testing and at one moment they decided to load the contributors of the restoration.
What I read in the report is that de bird did not fly any more since beginning of 2018, that means it did not fly for about half a Year before the accident flight. And was repainted shortly before. That really scared me. There is also no indication if it was sitting outside or hangared during those months.
Given all the other factors I mentioned earlier, this long idle time is a grave one. Even well maintained airliners, if they were parked outside for a week, You could come across some strange defects, mostly electrical/electronic though.
For a while I was a company test F/O for the flight(s) after heavy maintenance (D check) that also included a repaint job. The capt was also a dedicated test pilot, so normal cockpit structures ruled. We were specially trained for it, including non-STD manoeuvres and operations. And were expecting anything out of the ordinary, anytime.
The number of items we found were sometimes "countless", although many/most were minor. Add to that we sometimes were flying airliners from other carriers that had completely different instrument setups, different engines, etc. It took its toll on cockpit operations. But we were in the position to have "unlimited" time available to complete all tests, the flight took around 5-6 hours. That is longer than a test flight Boeing does on a new plane. If needed we redid a shorter test flight till all were satisfied. The first flight only mechanics/specialists that had some task to do in flight were allowed.
The Convair was sold under the "as is" condition. That leaves little room for the seller to spend a lot on test flying (fuel and other costs) and/or costly repairs.
That must have weighed heavily in the crew's decision process.
In all I do not envy the flight crew that was faced with so many contributing factors. You can only guess at what time one personally would have called it quits. IF you would have done.