Part3:
I like what you are doing this and I want this to succeed. I want to see more of good mouth flaps. However, when I see the code provided. I see multiple points I feel I shouldn't just leave like that.

So, here's some thing I'd suggest. Maybe you can learn too, the same way this presentation had things for me to learn.

Oversampling

Ren'Py already comes with oversampling out-of-the-box. You only need to use the "@" in the file name and Ren'Py takes care of oversampling for you.
Manual: https://www.renpy.org/doc/html/displaying_images.html#oversampling

Namespacing

I'd like if this example also made use of namespacing. In this case, it involves making us of the "in" modifier for python init.

E.g.
Instead of:

init python:

do:

init python in flapsAndBlinks:

This avoids clashing with functions of other libraries or the VN maker's

Choice

When doing choice, reduce repetition. Make use of the simple expression whenever viable. Ren'Py caches these expressions.

E.g.

alpha 1
choice:
    closed_eyes
choice:
    closed_eyes
choice:
    closed_eyes
    pause 0.05
    alpha 0
    pause 0.2
    alpha 1
    closed_eyes
pause 0.05

->

alpha 1
closed_eyes
choice 2:
    pass
choice:
    pause 0.05
    alpha 0
    pause 0.2
    alpha 1
    closed_eyes
pause 0.05

-----

alpha 1
choice:
    pause  0.1
    mouth_open
    pause  0.1
    mouth_half_open
    repeat 3
choice:
    pause  0.1
    mouth_open
    pause  0.1
    mouth_half_open
    repeat 6

->

alpha 1
pause  0.1
mouth_open
pause  0.1
mouth_half_open
choice:
    repeat 3
choice:
    repeat 6

(code is hard to type in itch....)

WhileSpeaking is intelligently made

The way you do this is smart:

def WhileSpeaking(name, speaking_d, done_d=Null()):
 return DynamicDisplayable(curried_while_speaking(name, speaking_d, done_d))

Finally

Thank you for making this tutorial. I hope it's picked up by many people and this can be used by many more people.