So isn't it accurate to say, since MCAS creates a pitching down moment by adjusting trim, it is effecting the final attitude of the aircraft...
Not accurate to say that. Yes, it is creating a pitch-down moment, but that moment doesn't necessarily result in any change to the final attitude of the aircraft.
Consider the aircraft being hand-flown in straight and level flight with the thrust at idle. In this situation, the speed is decaying, but to maintain level flight, the pilot is steadily increasing the rearward pressure on the control column. The aircraft is maintaining altitude but approaching the stall. Note that the pitch attitude is increasing (becoming more positive, or "nose high").
It is this situation (and similar) that Boeing had in mind when they conceived of the MCAS. Certification standards require the nose-down moment (or control column forces?) to linearly increase in this scenario, but Boeing found this wasn't happening satisfactorily and needed some way to impose more down moment - hence the MCAS.
In this same scenario, but with the MCAS working as designed, the pilot must exert a steadily increasing back pressure on the column in order to maintain level flight. The aircraft is now more stall resistant. This is what Boeing had in mind.
This example shows that there is no hard and fast link between MCAS operation and downward changes of pitch attitude. In fact, the pitch attitude has
increased throughout (become more positive, or "nose up"), with the effect of MCAS being to increase the control column forces being experienced by the pilot.
Or put very shortly: MCAS effects the pitch attitude of the plane.
No. MCAS
may affect the pitch attitude of the plane. Whether it does or doesn't depends on what else is going on. It was Boeing's belief that MCAS would
never affect the pitch attitude of the plane.