You’ve conceded that logic gates can be built with pneumatic (and other) systems. Complex logic systems were built, car automatic transmissions come to mind. I

You’ve conceded that logic gates can be built with pneumatic (and other) systems. Complex logic systems were built, car automatic transmissions come to mind. I don't know if there were Turing complete since there was no need - these were purposely built for a specific task. Anyway, analog computers are computers in that any realization of a Turing complete machine is necessarily created by analog circuits - albeit very non linear analog circuit. Therefore, Turing complete machines can be emulated on an analog computer but the reverse isn’t obvious - CFD, DFT, ad-initio can never really get the answer of the general case right (try simulating turbulence, crack propagation, the transition state of oxygen adsorbed on Pt under an applied external electric field etc)