The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7c88c31fb0addafdc13e5dc0264eceb37a987aa2

commit 7c88c31fb0addafdc13e5dc0264eceb37a987aa2
Author: Leo Zhang <googleo@chromium.org>
Date: Wed Feb 28 01:43:15 2018

Add Talkback-enabled options for re-ordering language settings.

Add move* options for each language item in a11y mode to help these
users move languages easily.
Tested in both normal mode and accessibility mode.

Bug:  814983 
Change-Id: Idb65d6dab6502be1b4e2bbc270b345282505ee5e
Reviewed-on: https://chromium-review.googlesource.com/938874
Commit-Queue: Leo Zhang <googleo@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539637}
[modify] https://crrev.com/7c88c31fb0addafdc13e5dc0264eceb37a987aa2/chrome/android/java/src/org/chromium/chrome/browser/preferences/languages/LanguageListBaseAdapter.java
[modify] https://crrev.com/7c88c31fb0addafdc13e5dc0264eceb37a987aa2/chrome/android/java/src/org/chromium/chrome/browser/preferences/languages/LanguageListPreference.java
[modify] https://crrev.com/7c88c31fb0addafdc13e5dc0264eceb37a987aa2/chrome/android/java/src/org/chromium/chrome/browser/preferences/languages/LanguagesManager.java
[modify] https://crrev.com/7c88c31fb0addafdc13e5dc0264eceb37a987aa2/chrome/android/java/strings/android_chrome_strings.grd

The bug should be fixed in the next canary soon

"Move up"/"Move down"/"Move to top" options are now available under language settings when talkback mode is on and working as mentioned above. Verified on latest M66-66.0.3358.0 in Samsung Galaxy S6 Edge plus(SM-G928G)/NRD90M