The arisaka action was tested by P.O. Ackley after the war, along with every mauser action variant, it was the only one that couldn’t be tested to failure.
Were they made rough and largely unfinished toward the end of the war, yes. None that haven’t been torch heated are unsafe. Good base for a custom rifle.
The nambu suffers from a competing sized cartridge, one should remember that size the average Japanese man was during the war for the answer to that riddle.
As for airplanes, had they had even a more competitive manufacturing ability most of Asia and the Pacific would be speaking Japanese, including all of china.
Ponder how much different Asia would have been during the 50-90s had a single country been in charge. Anyone think it would have been worse?
Over it all academically one had to be dishonest with the facts to think how it turned out was any better.