Screw are strong enough to hold any problematic forces and vibration on virtual model simulation and on the hundreds real frame that people already make. Nylock solve 99% of the problem you can have whit this locking system, moreover almost every mechanic forces are "taken" by the steel interlocked parts and not the screw.
Of course you have more advanced locking metal system but at wich cost??
The frame performance are already more than impressive ( go to read reviews on officials FB page from who daily use the frame) on this way for a very low cost (if you find a honest laser cut shop).
Why making complicated things when you can acceive same or better results with simplicity and cheaper?
The frame never go under resonance at any possible real speed/acc/jerk you can test in the reality.
And if you want the ultimate strength you can simply weld the frame with a TIG.
About 3/4" Baltic Birch plywood??? Is very nice for musical instruments because is resonating damn good.
And will be more expensive than the steel frame raw material and cnc cutting cost.
Furthermore our frame can be assembled by a 10 years old child in 30 minutes.
If you want examine better the design maybe you didn't noticed that the V1.1 is out since January 2018, with few improvements.