In Merriam-Webster, the third definition of "make" includes the following definitions I believe correspond to make as in "to make myself understood":
3 a : to cause to happen to or be experienced by someone [made trouble for us]
b : to cause to exist, occur, or appear : create [make a disturbance]
c : to favor the growth or occurrence of [haste makes waste]
d : to fit, intend, or destine by or as if by creating [was made to be an actor]
In addition, these definitions may fit as well:
5a: to cause to be or become [made them happy, makes it possible]
6 : to cause to act in a certain way : compel [make her give it back]
Question: Is the "Make" in "to make myself understood" referring to causing other people to understand you [by "forcing/making" them understand"], or rather causing or bringing about a state of which you are "understood".
Essentially, I think "make" could be seen also as "to cause to be or become" like "made them happy", which is recognizing merely a state change (not understood→understood) rather than referring to causing another person to understand you.
Do you make yourself understood (by others), or do you make yourself understood (into the state of understood/being understood)?