ChromeOS Version 65.0.3319.0 (Official Build) dev (64-bit) 
Firmware Version Google_Lulu.6301.136.57

Hi Alex,

Thanks for this very well-written bug. I see exactly what you mean here. I can reproduce it and would like to get one of our devs or designers to review it to determine if this is a bug or a feature request. 

Steps to repro:
# Go to Setting> Set Touchpad Scrolling to Australian (the default on my setup)
Note: "Australian scrolling" simply means that if you swipe up, the page moves up as opposed to "Traditional scrolling" which means that if you swipe up the page moves down
# Activate Accessibility/Screen magnifier
# Try to zoom in/out using Ctrl-Alt-(two-finger up/down)
Expected: the finger movement on the mouse pad/touch screen matches that of the scrolling settings. That is, if you scroll down, the the magnification goes down and if you scroll up the magnification size goes up. 
Actual: regardless of the scrolling setting, scrolling down increases magnification size (zooms in) and scrolling up decreases magnification size (zooms out). 

Thanks,

Laura 

+ @katie for her opinion

It makes sense to match the user's scroll settings. +lpalmaro to help prioritize.

Laura A, do you think the direction of scrolling to zoom in should change when the user has traditional vs Australian scroll setting on?

I'm seeing the opposite behavior for Ctrl-Alt + 2 fingers up:
Traditional zoom out
Australian zoom in
10452.96.0 (Official Build) stable-channel samus

It should be the other way around to match the documentation:
"Zoom in: Press Ctrl + Alt + Brightness up Increase brightness. You can also press Ctrl + Alt, then scroll with two fingers up."
https://support.google.com/chromebook/answer/6320705?hl=en&ref_topic=9016892

and for consistency with 2 finger zooming on Google Maps and Google Photos for example.

The way to think about it is that traditional scrolling moves the camera while Australian scrolling moves the content.  Swiping up (away from your body) should move the camera forward (zoom in), or conversely in Australian mode moves the content away from you (zoom out).