The phrase "you guys" is attempting to be evolved, by parties who use it currently, and don't want to change their behavior to be explicitly inclusive. I'm not going to speak to what's okay in other countries, but the English definition of Guys is from Guy Fawkes, and is intended to mean a man. I would be surprised if the etymology of that weren't the same for Australia, which was also a British colony.
But the last thing I will point out, is that it's not on the in-group "men" to say whether or not they're excluding people. It's the people who are being excluded who get to make that determination for whether or not they feel like there are barriers for them. So when men say "you guys" is inclusive, they're saying "I don't want to change my behavior, so this now includes everyone." And the thing that's being ignored is that there are people who don't agree that they are included in that phrase.
Gals comes across as even more old fashioned than actress in my region - it's a term that feels like it walked out of a movie old enough that it had to advertise that it had colour.
Sometimes, as the world evolves, gendered terms get replaced by new gender neutral terms. Sometimes the meaning evolves in different ways (e.g. doctor and nurse are no longer gendered equivalents of each other, as the division in roles has continued to be useful even after the gender stereotypes as to who does those roles slowly fades). And sometimes one term just subsumes the other.
And sometimes, these changes happened many decades ago in other countries that are not yours. It's not very inclusive to expect those people to defer to American expectations of those terms.