I have had some contact with some of these researchers, who are well-meaning but completely lost in all the pomo third wave feminist crazy.
They insist that this is a feminist project. What they are missing is that it is not a feminist project just because they say it is, it has to actually do something to improve the lives of women.
This project winds back women's rights. The changes in language which they are tracking are not some sort of random natural process in the evolution of ideas which benefit or disadvantage men and women equally. If you are just 'observing' the different ways that people use the terms 'sex' and 'gender' right now, then you are observing the patriarchy in action.
The researchers were surprised by the negative response to the survey. The reason that they had completely missed the outrage and frustration of women at the TRA takeover of the term 'woman' was because women have been systematically excluded from the public debate. Whether it was The Guardian deleting GC comments under its TRA articles or the widespread demonising of FPFW or Stonewall screams of transphobia if a woman stepped out of line, critical voices were sidelined and silenced.
I will give the researchers credit that they are making an effort to engage more widely to better understand the critical responses. The FAQs are an example of this. But I can't see how they are going to get past that pomo third wave thing to observe the shift in power which is underway.