I It's too bad the game doesn't allow the use of known 'blind spots' or am I missing something?
All two-seaters do of course have blind spots as they had in real. No one is shooting through the floor. Observers also do not shoot while under g-forces or too heavy manoeuvring etc., neither your observer nor AI. If the observers gun can aim downwards past the fuselage, they will do it of course. "Dead up from center" can also be a bit subjective, since you are moving and they are moving and one always can be slightly off the center for a moment.
BTW. blind spots and quality of observers, hitting or missing and shooting or not under g-forces etc. is for the player, flying two-seaters exactly the same as for AI. So another example of experiencing things sometimes subjective is that there are sometimes complaints about AI two-seaters sniping. They are not, but they are firing at you with the purpose to hit you. If flying somewhat after him, realtively to them you are slow and hardly moving, if not keep moving, trying to make it hard for them to train their guns on you. OTOH there are sometimes complaints that the own observer with the very same AI is not hitting a thing. So very subjective although the very same AI. Of course observers also have different skill levels.
Regarding system failures. Some engines were more prone for failure than others, but that it can happen sooner or later to any engine, is how it was. Also what kind of failure. I think in Ace-Pilot's case it was just bad luck. The next 50 flights there won't possibly happen anything