Please improve your figure 4. "Waterfall diagram of the moment and normal force at different actuation frequencies for the trailing edge flap(y-axis)".
Either submit the colour version of the figure or provide clearer B&W graphs.

And you should better replace the word "Waterfall" with "Campbell".
Though strictly spoken it is not a Cambell diagram as used in the classical sense for wind turbine design (where the rotor RPM is the variable along the x-axis).
But it has very similar use and interpretation i.e. the excitation frequencies (and in this figure even the magnitudes) of components (most times blades and tower) as a function of rpm.
Here the response of forces and moment on the t.e. flap actuation frequency.
And a "Waterfall plot"is such a general classification that it does not add a lot.

Success

Gerard van Bussel