Here we go... Finally something that's really up my alley

I'm both transgender and a linguist, so this is kinda my area of expertise.
What it comes down to is the following: there is increasing evidence that the brain actually produces multiple personalities for each language spoken. That means there's a whole referential framework for each language you speak, which also influences gender and gendered speech production.
And since you shouldn't take my word for it:
here' the paper I'm quoting.What this means, is that you will have to work on EACH of these different personalities that are invoked when speaking another language. Each and every one of them has to be adjusted, and working on the one doesn't necessarily change the other.
Me, I speak English, German, Dutch and French. The first three fluently, and my French is quite good, too. But since I don't use it that often (say: pre-transition was the last time I really got to used it more than a day in a row), my French still sounds quite masculine. This in the contrary to the other three languages, I use them on a daily basis and they've each been adjusted.
Cool, eh? Gotta love the human brain