Elaine Fuchs, the two sources you quote above are not exactly what I would like to see when I say that like should be compared with like. It is certainly and clearly the case that MTF transitioning will, on average, reduce someone's earnings, while FTM transitioning does not. That is to be expected, given that there is what is called male privilege and at least some sex-based discrimination in the labor force.
The crucial missing comparison, however, is between women who have never transitioned and trans women, and between men who have never transitioned and trans men, and probably should be done over long time periods as the stage of transitioning will have perhaps passing effects caused by transphobia and similar issues. In other words, a trans woman might still earn more in lifetime earnings than a woman who has never transitioned (even one who has not taken time off for having children), especially as the MTF transitions appear to take place later in life, on average, as mentioned in one of the studies you quoted.
That is of course an empirical question.
But it is also important to control for all other relevant variables, as I earlier stated, and that includes mental and physical health variables. In other words, the comparisons should be done between individuals with the same education, occupation, experience, physical and mental health and age. Neither of the two studies I looked at seem to include more than a few of the relevant variables.