It's so tempting to want to label them horizontal and vertical etc, but I have to work with Arabic which is all reversed, and then I'm setting up a test localization in Traditional Mongolian, and you realize why these things are named the way they are:

http://khumuunbichig.montsame.mn/index.php?home

CSS actually already accounts for that with it's "inline" and "block" axes. Where inline is the axis along which text flows first (horizontal by default for latin text - although this can be overiden with the writing-mode property), and block is the other axis. Flexbox's main axis controlled by flex-direction is an extra abstraction on top of that.

> http://khumuunbichig.montsame.mn/index.php?home

What's going on with the red text all the way on the left of the news items? It does not appear to be the same thing as the bichig...?

It's the date, I guess, written in a different set of numerals. Kinda like how Arabic writes the numerals different in many places.

You mean you have problem with start/end vs left/right? That's not confusing to me and helpful to use start/end for RTL layouts as well as LTR.