OS version 10.13.5:
When using the Chinese/pinyin input source, no matter whether one has
"Use the Caps Lock key to switch to and from last used Latin input source" option checked (in
System Preferences/Keyboard/Input Sources), the CAPS key is, by default, mapped as a toggle between pinyin and a Latin layout.
The issue here is that I want to be able to reclaim my CAPS key in spacemacs. However, I frequently write content in Chinese, so I would like to have a key to toggle Chinese/last-Latin that is not CAPS. The options in the System Preferences pane do not provide any means of reassigning this toggle-to-ABC shortcut to anything but CAPS and, what's worse, that option is vacuously satisfied due to the Chinese layout having already set it to CAPS by default.
I have peered around
/Library/Keyboard\ Layouts, but can't find where the values are stored, nor any means of manually editing this key in the terminal. I would prefer not to use software remapping.