There is no such thing as “Tznius-dig by the accepted standards of TODAY.” There is only Tznius-dig by the standards of the Torah and Chazal”
So do you think the Rabbonim of that time did not know about those standards then? Regardless of what you think, for those years, most non-chassidish frum women dressed a little differently than they do today, and I guarantee you every one of them would faint if she thought you were calling her immodest. When you call someone untzniusdig, you are making an extremely megative judgment about her character. Those women were nashim tzidkonios, most of them, and no one should be maligning them because they wore short sleeves or yes, even pants. There is a big difference between not dressed according to understood and accepted standards, and outright being untzniusdig. It seems to be a very difficult concept for some of you to chaap, though.
And I personally hold by the standard that expects a long enough skirt and sleeves and covered hair at all times, even in my house, btw when I am alone. But my mother O”H, one of the MOST eidel and balabatish frum women I have ever known, did not dress that way, until the last few years of her life. Very few frum women who grew up during WWII in the USA did. You impugn several generations of outstanding women, and it is not the right thing to do, as a Monday morning quarterback.