Last week on a forum somebody said something along the lines of: “Is it true that co-Masons call eachothers Brother regardless gender?” That seems to be a question with no easy answer.
At some point I ran into a book written by Karen Kidd, a woman who is referred to as “brother”. She also writes on a few places on the internet calling herself “brother Kidd”. Kidd is a member of the Honorable Order Of American co-Masonry. In her book about the history of this order “sisters” and “soeurs” (‘sisters’ in French) are mentioned, but it seems that along the lines, members of this order started to call eachother brothers.
This does not go for all mixed gender orders though. I -for one- have never heard any of my sisters being referred to as “brother”. Perhaps there are differences per country, perhaps per order.
Having said that, the female head of our lodge is a “worshipfull master”, not a “worshipfull mistress” (so: sister worshipfull master). I suppose this is not much different from calling a female painter a “painter” and not a “paintress”.
So the answer to the question is: “no”. Not all mixed gender lodges refer to every member as “brother”.