As a data point: they're both right-aligned in the original notification style, but not on Android - I believe Android doesn't right-align anything in System UI unless the system direction is set to RTL?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/685bcc0c2b065d1a51be73a2dac609e4265eea19

commit 685bcc0c2b065d1a51be73a2dac609e4265eea19
Author: Richard Knoll <knollr@chromium.org>
Date: Fri Dec 14 11:27:44 2018

fix: align rtl title in new style notification

New style notifications do not use a BoundedLabel for their title, which
renders RTL content right-aligned. Changed the aligment of the title
Label to gfx::ALIGN_TO_HEAD so that the behaviour is the same for title
and message.

Bug:  914437 
Change-Id: I99a316c6166385aa4f58b52da7cf7a15a6d5d2a9
Reviewed-on: https://chromium-review.googlesource.com/c/1375734
Reviewed-by: Peter Beverloo <peter@chromium.org>
Commit-Queue: Richard Knoll <knollr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616636}
[modify] https://crrev.com/685bcc0c2b065d1a51be73a2dac609e4265eea19/ui/message_center/views/notification_view_md.cc